DIAMETER | AREA|B.W.G Inch. Milli- | Circu- Square SquareNo. metres | lar inches. Milli-| Mils. metres.|0000 .454 11.5313 | 206116 .161883 10.4435000 .425 10.795 | 180625 .141862 9.15200 .38 9.6518 | 144400 .113411 7.31650 .34 8.6358 | 115600 .0907922 5.85731 .3 7.620 | 90000 .070686 4.56022 .284 7.2134 | 80656 .0633472 4.08673 .259 6.5784 | 67081 .0526854 3.39894 .238 6.0451 | 56644 .0444881 2.87015 .22 5.5879 | 48400 .0380133 2.45236 .203 5.1561 | 41209 .0323655 2.0887 .18 4.5719 | 32400 .0254469 1.64178 .165 4.1909 | 27225 .0213825 1.37949 .148 3.7591 | 21904 .0172034 1.109810 .134 3.4035 | 17956 .0141026 .909611 .12 3.0479 | 14400 .0113097 .729612 .109 2.7701 | 11881 .00933133 .6019913 .095 2.4129 | 9025 .0070882 .457314 .083 2.1082 | 6889 .00541062 .3490615 .072 1.8288 | 5184 .00407151 .248616 .065 1.6510 | 4225 .00331831 .2140717 .058 1.4732 | 3364 .0026421 .1704518 .049 1.2446 | 2401 .00188574 .1216519 .042 1.0668 | 1764 .00138544 .089420 .035 0.8890 | 1225 .000962115 .0620721 .032 0.8128 | 1024 .00080425 .0518822 .028 0.7112 | 784 .000615753 .0397223 .025 0.635 | 625 .00049087 .0316724 .022 0.5588 | 484 .000380133 .0245225 .02 0.508 | 400 .00031416 .0202726 .018 0.4571 | 324 .000254469 .0164227 .016 0.4064 | 256 .000201062 .0129728 .014 0.3556 | 196 .000153938 .0099329 .013 0.3302 | 169 .000132732 .0085630 .012 0.3048 | 144 .000113097 .007296
LENGTH AND WEIGHT
B.W.G Pounds Pounds Pounds Pounds Feet Yards 1.000 feet MilesNo. per per per 1.000 per per lb. per lb. per lb. per lb.foot. Yard ft. mile.0000 .623924 1.871772 623.924 3294.32 1.60276 .534253 .00160276 .00303553000 .54676 1.64028 546.76 2886.89 1.82895 .60965 .00182895 .003463900 .437105 1.311315 437.105 2307.92 2.28777 .76259 .00228777 .0043330 .349928 1.049784 349.928 1847.62 2.85773 .9525766 .00285773 .00541241 .272435 .817305 272.435 1438.43 3.6706 1.22353 .0036706 .00695192 .244151 .732453 244.151 1289.11 4.0958 1.365266 .0040958 .00775733 .203058 .609174 203.058 1072.15 4.9247 1.641566 .0049247 .0093274 .171463 .514395 171.465 905.333 5.8321 1.944033 .0058321 .01104575 .14651 .43953 146.510 773.56 6.8255 2.275166 .0068255 .0129276 .124742 .374226 124.742 658.638 8.0165 2.672166 .0080165 .0151837 .098076 .294228 98.076 517.844 10.1962 3.39873 .0101962 .0193118 .082411 .247233 82.411 435.135 12.1345 4.04483 .0121345 .0229819 .066305 .198915 66.305 350.089 15.0818 5.027266 .0150818 .02856410 .054354 .163062 54.354 286.99 18.398 6.13266 .018398 .03484511 .04359 .13077 43.590 230.152 22.9413 7.6471 .0229413 .0434512 .035964 .107892 35.964 189.893 27.805 9.2683 .027805 .0526613 .027319 .081957 27.319 144.245 36.6046 12.20153 .0366046 .06932614 .020853 .062559 20.853 110.1088 47.954 15.98466 .047954 .0908215 .015692 .047076 15.692 82.855 63.7267 21.24223 .0637261 .1206916 .012789 .038367 12.789 67.5276 78.1902 26.0634 .0781902 .1480917 .0101828 .0305484 10.1828 53.7665 98.202 32.734 .098203 .1858918 .00726795 .02180388 7.26796 38.3748 137.590 45.8633 .137590 .26058719 .00533972 .01601916 5.33972 28.1937 187.276 62.4253 .187276 .3546920 .00370815 .01112445 3.70815 19.579 269.676 89.892 .2696676 .5107521 .00309972 .00929910 3.09972 16.3665 322.610 107.5366 .322610 .6110022 .00237312 .00711936 2.37312 12.5301 421.384 140.4613 .421334 .79807823 .0018910 .0056757 1.8919 9.9892 528.570 176.190 .528570 .10010824 .0014650 .0043950 1.4650 7.7357 682.55 227.5166 .68255 .12927125 .00121082 .00363246 1.21082 6.39315 825.880 275.2943 .825883 .15641726 .00098077 .00294231 .98077 5.17844 1019.61 339.870 1.01961 .19310827 .00077492 .00232476 .77492 4.0916 1290.44 430.1466 1.29044 .2444028 .0005933 .0017799 .5933 3.13264 1685.48 561.8266 1.68548 .3192229 .000511571 .001534713 .511571 2.7011 1954.76 651.5866 1.95476 .37022030 .0004359 .0013077 .4359 2.30152 2294.13 764.710 2.29413 .434496
LENGTH AND RESISTANCE
B.W.G Feet Yards 1.000 feet Miles Ohms Ohms Ohms OhmsNo. per Ohm. per Ohm. per Ohm. per Ohm. per foot. per yard. per 1.000 per mile.foot.0000 19966.5 6655.5 19.9665 3.7815 .000050684 .00156252 .050084 .264443000 17497.15 5832.3833 17.49715 3.31385 .0000571522 .0001714566 .0571522 .30176300 13988.64 4662.68 13.98804 2.64925 .000071489 .000214467 .071489 .3774650 11198.17 3732.7333 11.19817 2.12086 .0000893002 .0002679006 .0893002 .4715051 8718.30 2906.10 8.71830 1.6512 .00011470 .0003441 .114701 .605622 7813.50 2604.50 7.81350 1.47973 .00012799 .00038397 .12799 .675803 6498.14 2166.0466 6.49814 1.23071 .00015389 .00046167 .15389 .812544 5487.107 1829.0357 5.487107 1.03923 .000182245 .000546735 .182245 .9622565 4688.51 1562.8366 4.68851 .887975 .000213287 .000639861 .213287 1.126166 3991.91 1330.6366 3.99191 .756045 .000250506 .000751518 .250506 1.322677 3138.59 1046.1966 3.13859 .59443 .000318614 .000955842 .318614 1.682288 2637.29 879.0966 2.63729 .499486 .000379177 .001137531 .379177 2.002069 2121.84 707.280 2.12184 .401864 .000471289 .001413867 .471289 2.48840510 1739.40 579.80 1.73940 .329432 .000574911 .001724733 .574911 3.0355311 1394.93 464.9766 1.39493 .264191 .000716882 .002150646 .716882 3.7851412 1150.91 383.6366 1.15091 .217976 .000868875 .002606625 .868875 4.5876613 874.252 291.4173 .874252 .165578 .00114383 .00343149 1.14383 6.0394514 667.338 222.446 .667338 .12639 .00149849 .00449547 1.49849 7.9120315 502.175 167.39166 .502175 .095109 .00199134 .00597402 1.99134 10.514216 409.276 136.42533 .409276 .077514 .00244334 .00733002 2.44334 12.900817 325.871 108.62366 .325871 .061718 .0030687 .0092061 3.0687 16.2027418 232.585 77.52833 .232585 .04405 .0042995 .0128985 4.2995 22.701419 170.879 56.95966 .170879 .032363 .0058521 .0175563 5.8521 30.899120 149.3915 49.797166 .1493915 .022475 .00842703 .02528109 8.42703 44.494721 99.195 33.065 .099195 .018787 .01008110 .03024348 10.08116 53.228522 75.9461 25.315366 .0759461 .014384 .0131672 .0395016 13.1672 69.523023 60.54377 20.181256 .06054377 .011467 .0165170 .0495510 16.5170 87.209624 46.8851 15.628356 .0468851 .0088798 .02132874 .06398622 21.32874 112.61625 38.748 12.916 .038748 .0073386 .025808 .077424 25.808 136.26526 31.3859 10.461966 .0313859 .0059443 .03186144 .09558432 31.86144 168.22927 24.79873 8.266243 .02479873 .0046967 .0403246 .1209738 40.3246 212.91428 18.98653 6.328843 .01898653 .0035959 .05266892 .15800676 52.66892 278.09229 16.3710 5.4570 .0163710 .0031006 .0610834 .1832502 61.0834 322.52130 13.9493 4.649766 .0139493 .0026419 .07168825 .21506475 71.68825 378.514
RESISTANCE & WEIGHT
B.W.G Ohms Lbs.No. per lb. per Ohm.0000 .000080272 12457.5000 .000104529 9566.700 .000163553 6114.240 .000255196 3918.581 .00042102 2375.182 .00052422 1907.593 .00075786 1319.504 .0010629 940.8445 .0014558 686.9116 .0020082 497.967 .00324863 307.8228 .00460101 217.3439 .00710791 140.68910 .0105772 94.54311 .0164462 60.84212 .0241593 41.39213 .0418692 23.883914 .0718583 13.916315 .126788 7.887216 .191045 5.234417 .301355 3.3183518 .59157 1.690419 1.09596 .91244520 2.27254 .4400321 3.25229 .3074822 5.54843 .1802323 8.73035 .1145424 14.5579 .06869125 21.3142 .04691726 32.4863 .03078227 52.0367 .01921728 88.7724 .01126529 119.404 .00837530 164.4762 .0060804
PURE COPPER weighs 555 lbs. per cubic foot. The Resistance of 1 mil. foot at 60° Fahr. is, according to Dr. Matthiessen, 10.32311 ohms. Upon these data the above Table has been calculated.
TheResistanceof Copper varies with the temperature about 0.38 per cent. per degree Centigrade, or 0.21 per cent. per degree Fahrenheit.
STRANDED WIRES.--With a conductor of a definite lenght, made ofStrandedWires, the totalweightisgreater, and theResistance lessthan is a similar length of Conductor with WiresnotStranded.
To convert--Inches to Millimetres multiply by 25.3994Feet to Metres " .3048Yards to Metres " .9144Miles to Kilometres " .6214Pounds to Kilogrammes " .45359
PEPARED BY WALTER T. GLOVER & CO., ELECTRICAL WIRE AND CABLE MAKERS, 25, BOOTH STREET MANCHESTER.
The gang mill is regarded as possessing material advantages in the rapid and economical manufacture of lumber. Among the recent improvements tending to perfect such mills, those which are shown in the iron frame stock gang, manufactured by Wickes Bros., East Saginaw, Mich., are eminently valuable. Our large engraving represents one of these mills, constructed to be driven by belt, friction, or direct engine, as may be desired. The important requisite in this class of mills is such design and proportion of parts as will insure durability and continued movement at the highest speed, safely increasing the quantity and improving the quality of work done at a lesser feed, and admitting the use of thinner saws than is practical in the slower moving sash. These are among the advantages gained in the iron frame machine, overcoming the necessity of an expensive mill frame, saving time and expense in setting up, and avoiding the liability of decay or change of position.
IMPROVED IRON FRAME GANG SAW MILL.
IMPROVED IRON FRAME GANG SAW MILL.
Many improvements have been made in the mechanism of oscillation, and from these the builders of this mill have adopted what is known as the Wilkin movement, which oscillates the top and bottom slides. The top slides are pivoted at the top end, and the bottom ones from the bottom end, both being operated by one rock shaft from the center. This movement when properly adjusted gives an easy clearance and the easiest cut yet obtained. It adds no extra weight to the sash, and avoids the cumbrous rock shaft and its attendant joints, usually weighing from three hundred to five hundred pounds, which have been found so objectionable in many other movements. The feed is continuous, and is made variable from ¼ to 1¼ inch to each stroke, controllable by the sawyer. Power is applied to the press rolls in the double screw form with pivot point, also operated by the same hand. A special feature of this machine is the spreading of the lower frame so that its base rests upon an independent portion of the foundation from the main pillow block or crank shaft. The solidity of the whole structure is thus increased, both by the increased width at the base and the prevention of connecting vibrations, which necessarily communicate when resting upon the same part, as in other forms of such machines heretofore in use.
The mill shown in the perspective view is one of twenty-six saws 4½ feet long, sash 38 inches wide in the clear, and stroke 20 inches, capable of making 230 strokes per minute. The crank shaft is nine inches in diameter, of the best forged iron. The main pillow block has a base 6½ feet long by 21 inches bearing, weighing 2,800 pounds. The cap is secured by two forged bolts 3½ inches in diameter, and by this arrangement no unequal strain upon the cap is possible. A disk crank is used with suitable counterbalance, expressly adapted to the weight and speed of sash; a hammered steel wrist pin five inches in diameter, and a forged pitman of the most approved pattern, with best composition boxes. The iron drive pulley is 4 to 4½ feet in diameter and 24 inches face; the fly-wheel six feet in diameter, and weighing 4,700 pounds, turned off at rim. When a wider and heavier sash is required, a proportionate increase is made in all these parts.
In the construction of the sash the stiles are made of steel; the lower girt and upper heads are made in one solid piece, without rivets, giving the greatest strength possible, with the least weight. The outfit also includes eight iron rollers for the floor, 8½ inches in diameter, with iron stands, and geared as live rolls when desired, a full set of Lippencott's steel saw hangings, and gauges for one-inch lumber. The weight of the machine here shown is 18½ tons. They are, however, built in larger or smaller sizes, adapted to any locality, quality or quantity of work desired.
It is said that the St. Gothard Tunnel is diverting the bulk of the Italian trade into the hands of the Belgians, Germans, and Hollanders with startling rapidity. Without breaking bulk, early fruits are taken from all parts of Italy to Ostend, Antwerp, and Rotterdam, whence they are carried by fast steamers to London and other English ports. But, on the other hand, Germany is sending into Italy large quantities of coal, iron, machinery, copper, and other articles of which the latter received nothing before. In two months alone, the Italians imported 1,446 tons of paper.
The system of heat regeneration in the firing of gas retorts, in accordance with the principle which Dr. C.W. Siemens has worked out in such a variety of ways in the industrial arts, has lately been applied with very marked success at the Dalmarnock Station of the Glasgow Corporation Gas Works. Notwithstanding the fact that a period of about twenty years has elapsed since Dr. Siemens successfully adapted his system to the firing of retorts at the Paris Gas Works, it seems to have made but little progress up to the present time; for what reasons it is perhaps difficult to explain. It is certain, however, that so-called regenerator furnaces of various forms have, from time to time, been brought into use at gas works for the purpose in question both on the Continent and in this country; and in recent years the subject has received much attention from gas engineers, the general opinion eventually being that the adoption of such a system of working would be certain to result in so great an amount of economy as to put gas as an illuminating agent on a more secure footing to compete successfully with its modern and somewhat aggressive rival, the electric light. Of course, it is now admitted that the mode of adapting the heat regenerative principle at the Paris Gas Works was attended with a degree of complexity in the structural arrangements that was so great and so expensive as to place it practically beyond the reach of gas companies and gas corporations generally, when the expense as well as the scientific beauty and practical efficiency of the new mode of applying and utilizing heat had to be considered. Fortunately, however, Dr. Siemens was enabled two or three years ago to demonstrate that there was no such thing as "finality" in that department of invention which he had made almost exclusively his own. About the time mentioned he placed his most advanced views on gas producers and on the regeneration and utilization of heat before the world, and within that period a most decided step in advance has been made, the structural arrangements now required for gas producers and regenerator furnaces having been immensely simplified and cheapened, while their practical utility has in no way been interfered with.
Scarcely had Dr. Siemens announced his new form of gas producer and regenerator than communication was opened with him by Mr. W. Foulis, the general manager to the Glasgow Corporation Gas Trust, with the view of entering into arrangements for its adoption on an experimental scale at one of the stations under his charge. Encouraged by the hearty co-operation of the gas committee, two or three of whose members were well known engineers, Mr. Foulis very soon came to an understanding with Dr. Siemens to have the regenerative system put to a thorough test at the Dalmarnock Gas Works, situated in the extreme east end of the city, and the largest establishment of the kind in Scotland, the total number of retorts erected being about 750. The system in its most recent shape was applied to four ovens, each of which had seven retorts, but which number has since been increased to eight, owing to the space occupied by the furnace in the ordinary settings being rendered available for an additional retort in the new or "Siemens" setting. For each oven or chamber of eight retorts there was erected a separate gas-producer, so that even one set of eight retorts might alone be used if thought necessary.
GAS RETORTS WITH REGENERATIVE FURNACES .--GLASGOW CORPORATION GAS WORKS.
GAS RETORTS WITH REGENERATIVE FURNACES .--GLASGOW CORPORATION GAS WORKS.
In Figs. 1 and 2 of our illustrations, the general arrangement and the relationship of the gas producer, the regenerators, and the retorts to each other are clearly shown. It was a sort ofsine qua nonof the new method of firing the retorts that the producer should be in as close proximity as possible to the place where the gaseous fuel was to be used, and it was concluded that the most convenient situation would be immediately in front of its own set of eight retorts, and with its top on a level with the working floor of the retort house. To place it in such a position meant a good deal of excavation, which was also required, however, for the regenerator flues. The excavation was carried down to a depth of 10 ft. below the level of the retort house floor, and as a matter of course the operation of underpinning had to be resorted to for the purpose of carrying down the foundations of the division walls, which, together with the main arches and the hydraulic main, were in no way otherwise disturbed. As in most new inventions, a good deal of difficulty was experienced at first in connection with these gas producers and heat regenerator furnaces; but by dint of application and by the adoption of modifications made here and there in the arrangements from time to time, as also by a determination not to be beaten, although often disheartened, Mr. Foulis was ultimately rewarded with complete success. The new system of firing being made so simple that there was scarcely any possibility of failure likely to arise in ordinary practice if it was superintended with but a moderate amount of care.
Fig. 3.
Fig. 3.
The results which were obtained in course of time with four ovens, or a total of 32 retorts, were so exceedingly promising that it was forthwith resolved to extend the new mode of firing to the whole of a double bench of twelve ovens, now containing 96 retorts; and all the improvements which had suggested themselves during the working experiments with the four ovens were adopted from the first in the reconstruction of the remaining eight ovens in the bench. More recently the regenerator system has been applied to other 22 ovens, or 176 additional retorts, being the whole of one of the main divisions of the retort house; and during the very depth of the present winter, when the demand for gas was at its greatest height, all the retorts of the converted or "Siemens" settings, amounting to 272, were in full working activity, in which condition they still remain. It is intended to make another very considerable extension of the heat regenerative system of firing during the ensuing spring and summer. The reconstruction of the present year will extend to the ovens of seven retorts each, giving in this case eighty gas fired retorts; and to twenty ovens of five retorts each, which will become sixteen ovens, each having eight retorts, making 128 retorts in this division, and the total being 208 retorts in place of 170 in the same amount of space. It is confidently anticipated, therefore, that by the month of August of the present year, 480 full sized retorts will be available for working out the new method at the Dalmarnock Gas Works. Furthermore, the confidence which has been inspired in the minds of the members of the Glasgow Corporation Gas Committee and their engineer regarding the actualities and possibilities of the Siemens system of firing gas retorts, in its most improved state, is such that arrangements are being made for starting shortly to apply it throughout at the Dawsholm Station, which is situated in the suburban burgh of Maryhill, and some four or five miles distant from the Dalmarnock Works in a northwestern direction. The station just named, which is also a very large one, will probably require two years for its conversion.
We shall now give some account of the structural arrangements adopted for producing cheap gaseous fuel, and for turning that fuel to the greatest advantage in firing the retorts for the purpose of carbonizing the cannel coal used as the source of the gas.
The gas producer, which is represented in vertical section in Fig. 2, is a cylinder of brickwork inclosed in a casing of malleable iron. It is 7 ft. 6 in. deep, and 3 ft. in diameter, which becomes reduced to 20 in. above, where it is closed by means of a cast-iron lid, which is continuous with the floor of the retort house. There are no firebars at the bottom, so that the fuel rests on a floor of firebrick. At the bottom of the walls of the producer there are several holes about 1 ft. in length by 6 in. in height. By means of these openings any clinker that may form and the ashes of the spent fuel can readily be withdrawn. They also allow of the admission of air to maintain the combustion in the lower portion of the mass of fuel; and at each opening there is a malleable iron tube for delivering a jet of steam direct from a steam boiler. We shall subsequently explain the functions performed by the steam.
The fuel employed is the coke or char resulting from cannel coal when it has yielded up its hydrocarbons and other gases during the process of carbonization in the gas retorts. Being entirely made from Scotch cannel the coke is very poor in quality, as it contains a large percentage of mineral matter or ash relatively to its fixed carbon. The retorts are worked with three-hour charges, but the producer is only charged once in every six hours For each set of eight retorts the charge of raw cannel is about 18 cwt., and it is found in practice that the coke drawn from five of the retorts is quite sufficient to fill up the producer to the top. Formerly a set of seven retorts fired in the ordinary way from a furnace underneath, required from 60 to 75 per cent. of the coke made, but now, with eight retorts in each oven, the quantity has been reduced to about 30 per cent., or less than one-half of what it formerly was. Before the retorts are drawn the lid is removed from the top of the producer, and any fuel still remaining unconsumed is touched up a bit by way of leveling it on the surface, and as soon as it has been filled up to the constricted portion a shovelful of soft luting is spread over the top of the coke, and the lid is laid upon it and driven home, thereby making a perfectly air-tight joint. The contents of the other three retorts, as also the contents of the whole of the retorts at each alternate drawing, are taken to the coke heap in the yard. We have already spoken of a charge of cannel as being about 18 cwt. for each set of eight retorts, but in connection with that matter we should mention that it was formerly about 13 cwt. per oven containing seven retorts, and that there is every prospect of it being increased without increasing the length of time occupied in carbonizing the cannel of each charge.
It may be worth while now to notice briefly what takes place among the mass of coke in the gas producer. The atmospheric air admitted at the several openings previously spoken of ascends through the lower layers of the incandescent coke, the carbon of which burns to carbonic acid gas at the expense of the oxygen of the air. Among the middle and upper layers of the incandescent coke the carbonic acid gas takes up a further quantity of the fixed carbon, and becomes transformed into carbonic oxide gas (CO2+C=2CO), which is an inflammable body, and possesses considerable calorific power. Unless the carbonic acid gas is very completely "baffled" in its ascent through the coke in the producer, a quantity of it passes into the furnace along with the carbonic oxide, the efficiency of which is diminished in proportion as the former increases in quantity. Of course, also, the nitrogen associated with the oxygen in the air admitted to the gas generator passes on with the carbonic oxide gas, this nitrogen acting as a dilutant and being of course absolutely useless as a generator of heat. The steam which we previously spoke of serves two good purposes. In contact with incandescent coke it suffers decomposition, its oxygen uniting with some of the fixed carbon to form carbonic oxide, while the hydrogen which is set free passes onward, and mixes with the other gases to be subsequently consumed with them. The admission of the steam thus causes the absorption of heat in the gas generator where the decomposition takes place, this heat being again evolved on the subsequent combustion of the hydrogen. Then, again, as the steam is delivered in among the coke in a jet, or a series of jets, it has the effect of almost entirely preventing any clinkering or slagging of the earthy and silicious materials, which form such a large portion of the substance of the coke obtained from Scotch cannels, sometimes as much as from 15 to 20 per cent. It is scarcely necessary for the stokers to go down below to the bottom of the producers to remove the ash above once in every six hours. Referring to the composition of the gaseous fuel obtained from cannel coke in one of these gas producers, we give the following typical analysis on the authority of Dr. William Wallace, F.R.S.E., gas examiner, and one of the public analysts for the city of Glasgow:
Per cent.Hydrogen 8.7Carbonic oxide 28.1Carbonic acid 3.5Oxygen 0.4Nitrogen 59.3-----100.0
By again referring to Fig. 2, it will be observed that an opening is provided for the passage of the gaseous matter as it is formed into the mass of brickwork, the upper half of which is occupied by the retorts of the setting and the lower by the regenerators.
Before following the gas we may first direct attention to the arrangements for dealing with it, and with the air that has to be admitted for the combustion of so much of it as is of a combustible nature. It will be seen by reference to Fig. 1 that the oven proper is occupied by eightshaped retorts. These are 9 ft. long (set back to back) by 18 in. by 13 in., and they are placed on arches which are 8 ft. 6 in. wide. Underneath the level of the retort oven there are two regenerators or regenerator chambers, which differ very materially in form from the regenerators formerly applied by Dr. Siemens to gas retort ovens, and which are still employed for high temperature furnaces like those used for steel and glass melting. In the case of these latter the regenerators are on the alternating system--that is to say, a mass of brickwork is heated by the waste heat of the effluent gases, and when that is made sufficiently hot, the current of waste gases is turned into a second mass of brickwork, while air is admitted to pass through the brickwork already heated. The system thus briefly described entails a certain amount of attention on the part of the workmen in the altering of the valves or dampers to reverse the currents. The regenerator now adopted consists of an arrangement of six zigzag flues, three on each side of the setting. These flues run the whole length of the setting. As indicated by the arrows pointing downward in Fig. 3, the waste gases on their way to the chimney stack pass to and fro through the side flues, thus giving up a large portion of their contained heat by the process of conduction or contact to the central flue through which the incoming air passes. The air necessary for combustion is first admitted into a large chamber in the center, and then it is divided into two currents, which pass right and left into the central passages of the two regenerators. As the air flue is at a very bright heat for a considerable distance before the air leaves it, the temperature of the air must be equally great, or nearly so. In its most improved form one of these heat regenerative furnaces provides an amount of heating surface extending to 234 square ft., which is exposed to the air on its way to the combustion chamber.
Passing from the producer through the flue provided for it, the gas enters the retort setting underneath the side retorts, where it meets the air coming from the regenerator. It enters the setting, not by a number of small openings, but by one large opening on each side, and meets the air entering also by a large opening, the effect of which is to avoid the localization of intense heat, as all the retorts of the setting become enveloped in an intensely heating flame, due to the combustion of the carbonic oxide and hydrogen gases.
There are various advantages attending this system of firing gas retorts. First of all, there is already a saving of fuel to the extent of one-half, and not unlikely there will soon be a further very decided increase in the saving of fuel to record, inasmuch as it has been experimentally determined within the past two or three weeks that, by increasing its diameter to 3 ft. 4 in., one producer can be made to provide a sufficient amount of gaseous fuel to fire two sets of eight retorts. By the arrangement just hinted at the relative amount of fuel used will be still further reduced. Then, again, an additional retort can well be placed in each oven, as it occupies the position of the fire in ordinary settings. In the third place, by the greater heat which is obtained, the charges can be more rapidly distilled; or heavier charges can be carbonized in a given space of time. When all the gains are put together, the amount of coal carbonized is increased by about 40 per cent. over any specified time. Of course, in the new or regenerator settings there is much greater regularity of heat; and as the gaseous fuel is perfectly free from all solid matter, and burns without any trace of smoke, there is a total absence of deposit on the outside of the retorts. From these two circumstances combined it is but natural to expect that there should be greater durability of the retorts--which is really the case. Another advantage is that, as the fuel used in the furnaces is wholly gaseous, choking of the flues cannot by any possibility arise. It is the confident opinion of Mr. Foulis that the system in question can be applied with advantage to all sizes of gas works, and that it is certainly well adapted for all works where the summer consumption of gas is sufficiently large to give employment to eight retorts.
As this is the first instance of the new form of gas producer and regenerator having been adopted in any gas works, a very great amount of scientific and practical interest attaches to it. Many persons have visited the Dalmarnock Gas Works during their reconstruction, in order to see the system in operation, and doubtless many more will go and do likewise when they learn of the numerous advantages which it possesses, and which are likely to increase rather than diminish.--Engineering.
During the past few weeks, a highly interesting experiment--and one, moreover, destined to materially influence the development of the uses of gas in a fresh field--has been in progress, under the guidance of Mr. Booer, at a baker's shop in the Blackfriars Road, London. The experiment in question is nothing less than the application of gas for heating bakers' ovens, in a manner not hitherto attempted, and such as to bring the system within the means of the poorest tradesman in all but the smallest towns. It will be remembered that the success of the gas-heated muffles for burning tiles and glass led to the attempted construction of a model baker's oven, heated by the same fuel, which was shown in action at the Smoke Abatement Exhibition at South Kensington in the winter of 1881-82. This model attained considerable success; but its design demanded either a new structure in every case, or considerable alteration of any existing oven. In the proposed system, moreover, the oven was heated wholly from without--a condition supposed to be necessary to meet the objections of the bakers. It is evident, however, that there must be considerable waste of gas in heating a mass of tiles and brickwork, such as go to the construction of a common baker's oven, from the outside; and the objection to handicapping such a costly fuel as gas in this manner becomes more apparent when it is remembered that in the usual way the oven is always heated by an internal coal fire. When it is further considered that the coal commonly used by bakers is of the most ordinary quality, full of dirt that would condemn it in the estimation of a gas manager, the sentimental objection to allowing a purified gas flame to burn in a place which this rubbish is permitted to fill with foul smoke becomes supremely ridiculous. Consequently, when Mr. Booer, whose work in connection with the gas muffle is well known in England and America, seriously addressed himself to construct, upon altogether new lines, a cheap and practical baker's oven, he wisely put the gas inside.
There are many other conditions which Mr. Booer, after consultation with practical bakers and others, set himself to fulfill, the observance of which lends to the present Blackfriars experiment much of its interesting character. Thus it was observed that, while it is not difficult to build an oven in a given spot, and bake bread in it, this cannot truly be called abaker'soven. By this term must be understood in particular an oven in an ordinary bakehouse, set in the usual style and worked by a man with his living to get by it. Before the problem of extending gas to bakers' ovens could be considered solved, it had to be attacked from this aspect. Mr. Booer, to do him full credit, seems to have early appreciated this fact in all its bearings. He not only saw that it was necessary to save gas, as much as possible, by putting it inside the oven; but he was told that, in order to meet with any general success, the cost of converting an oven to the gas system must be rigidly kept down to about ten or twelve guineas. The latter seems a particularly hard condition, when it is remembered that the only improved baker's oven in practical use at the present day is the steam oven invented by Mr. Perkins, which costs two or three hundred pounds to erect. Mr. Booer also had in mind the necessity that everything possible for a coal oven must likewise be performed by a gas oven; and in this respect he set himself to surpass the costly Perkins oven, which will not bake the common "batch" or household bread, generally the principal article of sale, more especially in populous and poor neighborhoods. The peculiar efficacy of the common coal fire in this respect proceeds from the essential principle of action of a brick oven, which is found simply in the fact that the work is done entirely by heat previously imparted to the tile bottom, roof, and sides of the oven, and thence radiated to the bread. No other kind of heat will bake batch-bread--i.e., loaves packed in contact with one another--which requires to be thoroughly soaked by a radiant heat in a close atmosphere of its own steam. Now, as a coal fire is eminently qualified to impart, by radiation and otherwise, this necessary store of heat to the brickwork, it is plainly a difficulty to effect the same purpose with a fuel which, of itself, can scarcely radiate heat at all. The system of the gas cooking-oven--the utilization of the heat of the combustion products as formed--is clearly inapplicable here; for a different kind of heat is needed, under conditions that would not sustain continuous combustion. Therefore, there is nothing for it but to heat the bottom and sides of the brick oven by the direct contact of powerful gas-flames; thus supplanting the coal fire, but leaving the actual work of baking to be done afterward by stored-up heat in the regular way.
Having settled the general principles of a system of this kind, there still remain a number of scarcely less important details, in the dealing with which lies the difference between practical success and failure. Thus it is not merely sufficient to heat an oven for bread baking; it is also necessary to heat it within the times and according to the habits of work to which the baker has been accustomed. Work in town bakeries begins at about midnight, or shortly after, and the condition of the oven must conform to the requirements of the dough, which vary from day to day and from season to season. In order to master all these niceties, as far as a knowledge of them is necessary to his purpose, Mr. Booer has spent many nights in the bakehouse in the Blackfriars Road; and has thereby obtained a command over the technicalities of the work which has served him in good stead, not merely for adjusting his gas heat, but in answering the innumerable objections always raised when a revolution in an immemorial trade is threatened. It is with considerable satisfaction that we are enabled to declare, after duly weighing all the conditions as to first cost and otherwise imposed by himself and others, that Mr. Booer has succeeded, upon these terms, in vindicating the claims of gas to be a cheap, efficient, and cleanly fuel for heating ovens under the control and according to the methods of working of the baker himself.
The oven with which this success has been achieved is one of two in the bakehouse of Mr. Loeber, of 161 Blackfriars Road. It measures 7 feet by 6 feet internally; being what is technically termed a 6 bushel oven. The alterations made by Mr. Booer consist in the first place in the removal of the flooring tiles, and the laying down of a new bottom, under which run a number of flues radiating from the side furnace. The throat of the furnace, where it enters the angle of the oven, is bricked up, and eight pieces of ¾-inch gun-barrel tubing project above this dwarf wall, and radiate fan-shaped under the dome of the roof. These are the gas-burners, which are supplied from a 1½-inch pipe led into the old furnace. The same pipe supplies the similar burners which are inserted in the flues under the oven bottom. This is really all the plant required. It should be remarked that these bottom flues are carried to different points of the side walls, and the products of combustion are allowed to rise upward into the oven through gaps left for the purpose. A supplementary supply of heated air is provided to help the combustion of the gas in these flues, which would otherwise be languid. When the gas is turned on from the main cock in the furnace either to the top or the bottom set of burners, a long match is used to light them from the same point. This is effected without risk of firing back, by the adoption of a specially constructed atmospheric nipple and shield, the pattern of which is registered. The flame from the top burners unites in a sheet of fire, which spreads out all over the crown of the oven, at the same time that the burners below are doing their work, and the products of combustion flow together through the oven to the chimney, which is the same that was used for coal. At first, as might be expected, there was considerable difficulty in finding the most suitable position of the chimney damper, aggravated in this case by the fact that the other oven worked with a coal fire into the same shaft. Finally, however, the two flues were disconnected with the happiest results. During the past fortnight the oven has been in regular use, and the bread has been sold over the counter in the ordinary course of trade. Two and three batches of bread have been baked in one day in this oven; the economy of its use, of course, increasing with the number of loaves turned out. As a rule the gas is lighted for about an hour before the oven is wanted, and about 250 cubic feet are used. Then the cocks are shut and the oven is allowed to stand closed up for ten minutes, in which time it ventilates itself, and the heat spreads over it. Then the batch is set, and the baking occupies from an hour to an hour and a half, according to the different classes of loaves. Two batches are baked with a consumption of about 620 cubic feet of gas; costing, at 2s. 10d. per 1000 cubic feet, just 11d. each batch for fuel. This cannot be considered costly. But the system possesses many other advantages. In the first place, it is much more cleanly than coal; for the oven never requires wiping out, which is usually done with a bundle of old rope called a "scuffle" and the operation is attended with a most unpleasant odor. Then there is no smoke--a great advantage from the point of view of the Smoke Abatement Institution. More to the purpose of the journeyman baker, however, is the fact that there is no stoking to be done, and he can therefore take his repose at night without having to attend to the furnace. Besides this the master has the satisfaction of knowing that the oven will always be hot enough if he simply attends to the time of lighting the gas--a consideration of no small moment. It is no mean testimony to the reality of Mr. Booer's success that Mr. Loeber, having seen his difficulties and troubles from the beginning, and marked how they have been overcome, is content to acknowledge that even this first example is capable of turning out bread in a condition to be sold over the counter. There is a good opening in this direction, for there are 6,000 bakeries in London alone, to every one of which Mr. Booer's system might be applied with advantage to the tradesman and his customers. And what may be done with gas at about 3s. per 1,000 cubic feet may certainly be done to still greater advantage in many towns where the price is lower. Mr. Booer has entered upon his work in a proper spirit. He has begun at the beginning, with the necessities of the baker; and has gone plodding on quietly, until he has achieved a noteworthy success. It may be hoped he will receive the reward which his perseverance merits.--Jour. of Gas Lighting.
Who was drowned on July 24 in attempting to swim through the whirlpool and rapids at the foot of the Falls of Niagara, was born at Irongate, near Dawley, in Shropshire, January 18, 1848. He was 5 feet 8 inches in height, measured 43 inches round the chest, and weighed about 14½ stone. He learnt to swim when about seven years old, and was trained as a sailor on board the Conway training-ship in the Mersey, where he saved the life of a fellow seaman. In 1870 he dived under his ship in the Suez Canal and cleared a foul hawser; and, on April 23, 1873, when serving on board the Cunard steamer Russia, he jumped overboard to save the life of a hand who had fallen from aloft, but failed, and it was an hour before he was picked up almost exhausted. For this he received a gold and other medals. He became captain of a merchant ship, but soon after he relinquished the sea and devoted himself to the sport of swimming.
At long distance swimming in salt water he wasfacile princeps, but he did not show to such advantage in fresh water. In June, 1874, he swam from Dover to the North-East Varne Buoy, a distance of 11 statute miles. On July 3, 1875, he swam from Blackwall Pier to Gravesend Town Pier, nearly 18 statute miles, in 4 hours 52 minutes. On the 19th of the same month he swam from Dover to Ramsgate, 19¼ statute miles, in 8 hours 45 minutes. On August 12, 1875, he tried to cross from England to France, and although he failed, owing to the heavy sea, he compassed the distance from Dover to the South Sand Head, 15½ statute miles, in 6 hours 48 minutes. On the 24th of the same month he made another attempt, which rendered his name famous all over the English-speaking world. Starting from Dover, he reached the French coast at Calais, after being immersed in the water for 21 hours 44 minutes. He had swum over 39 miles, or, according to another calculation, 45½ miles, without having touched a boat or artificial support of any kind. Subsequently he swam at the Lambeth Baths, and the Westminster Aquarium, and last year, at Boston, U.S., he remained in a tank nearly 128½ hours. Latterly he had suffered from congestion of the lungs, and his health had become much impaired.
CAPT. MATTHEW WEBB.
CAPT. MATTHEW WEBB.
The story of his final and fatal effort needs here but a brief description. At two minutes past four, on July 24, Webb dived from the boat opposite the Maid of the Mist landing, and, amid the shouts and applause of the crowd, struck the water. He swam leisurely down the river, but made good progress. He passed along the rapids at a great pace, and six minutes after making the first plunge passed under the Suspension Bridge. Immediately below the bridge the river becomes exceedingly violent, and as the water was clear every movement of Webb could be seen. At one moment he was lifted high on the crest of a wave, and the next he sank into the awful hollow created. As the river became narrower, and still more impetuous, Webb would sometimes be struck by a wave, and for a few moments would sink out of sight. He, however, rose to the surface without apparent effort. But his speed momentarily increased, and he was hurried along at a frightful pace. At length he was swept into the neck of the whirlpool. Rising on the crest of the highest wave, he lifted his hands once, and then was precipitated into the yawning gulf. For one moment his head appeared above the angry waters, but he was motionless, and evidently at the mercy of the waves. He was again drawn under the water, and was seen no more alive. Some days later his body was found four miles below the fatal Rapids. It bore tokens of the fearful violence of the struggle which he had undergone. His bathing drawers were torn to fragments, and there was a deep wound in his head. An inquest was held, and the jury returned a verdict of "Found drowned."
Captain Webb was married about three years ago, and leaves a widow and two children. It is understood that he risked his life in this last fatal attempt to obtain money for the support of his family.--London Graphic.
These houses are situated in a pleasant part of Headingley, which is the favorite residential suburb in the locality of Leeds. As regards accommodation, the ground-floor of each house comprises good-sized drawing and dining rooms, each with bay windows; well-lighted entrance halls, opening upon wooden verandas; kitchen, pantry, and scullery; on first floor are three good bedrooms, a bathroom, and other necessary accommodation; on second floor are two additional bedrooms. The basement contains coal-place and larder.
In these houses an attempt has been made to produce conveniently-planned and well-arranged habitations, combined with a pleasing and picturesque exterior, without involving a large outlay of money. The materials used are brick of a deep red color for facings, red terra-cotta from Messrs. Wilcock & Co., of Burmantofts, for moulded strings, sills, etc., and a very sparing use of stone from the Harehills Quarries. The front gables are constructed of timber in solid scantlings, well framed, and pinned together with oak pegs, filled in and well backed behind with brickwork; the panels faced with cement, which, together with the cored cornice, are finished in vellum color. The whole of the woodwork of exterior is painted a neutral shade of peacock blue, forming an admirable contrast with the deep red of the bricks, the sashes and casements only being finished in cream color. The whole of the chimneypieces in the interior are carried out from the architect's special design; those in the drawing-rooms being of mahogany, finished in rosewood color, and those in dining-rooms of oak, stained with ammonia and dull wax polished.
SUGGESTIONS IN ARCHITECTURE.--SEMI-DETACHED VILLAS,BROMFIELD CRESCENT, HEADINGLEY, LEEDS.
The houses, with outbuildings and boundary walls, which have been erected for Mr. John Hall Thorp, of Bromfield, Headingley, have cost £1,450, or thereabouts, this amount not including the price of land. They have been carried out from the designs and under the superintendence of Mr. William H. Thorp, A.R.I.B.A., architect, of St. Andrew's Chambers, Park Row, Leeds.--The Architect.
In view of the possible approach of cholera, and the sanitary precautions that even the most neglectful of authorities are constrained to take, it is of some interest to us, says theBuilding News, to know how the poor are housed in the city of Paris, which contains, more than any city in the world, the opposite poles of luxurious magnificence and of sordid, bestial poverty. The statistics of the Parisian working classes in the way of lodgings are not of an encouraging nature, and reflect great discredit on the powers that be, who can be stern enough in the case of any political question, but are blind to the spectacle of fellow creatures living the life of beasts under their very eyes. In 1880, the Prefect of Police gave licenses to 21,219 arrivals in the city of French origin, and to 7,344 foreigners. In the succeeding year, the former had increased to 22,061, while the latter had somewhat diminished, being only 5,493. There was a census taken in 1881, from which it appeared that Paris contained 677,253 operatives and 255,604 employes and clerks, while out of every 1,000 inhabitants, 322 only were born in the city, and 565 came from the departments or the French colonies. The foreign element in the working classes has increased very rapidly, numbering 119,349 in 1876, to which by 1881 there was an addition of 44,689. To every 1,000 inhabitants, Paris now numbers 75 foreigners, though in 1876 the proportion was only 60. It may not be amiss to state that the annual increase of the Paris population is at the rate of 56,043 persons, and that in the five years 1876-81, the city received 280,217 additional mouths. The total population of the capital is 2,239,928, of whom 1,113,326 are males.
Returning to the poorer classes, we find that in 1872 they were estimated at 100,000; but that in 1873 they had risen to 113,733, and in 1880 to 123,735. It is unfortunate to be obliged to say that the majority of these people are housed worse in Paris than in almost any other great city in the world. There are two classes of lodgings for the poor--the one where the workman rents one or more rooms for his family, and, perhaps, owns a little furniture; the other, a single room tenanted for the night only by the unmarried man who pays for his bed in the morning and gets his meals anywhere that he can. Readers will remember how, under the auspices of M. Haussmann, western Paris was almost pulled down and transformed into a series of palatial boulevards and avenues. While the work lasted the Paris workman was well pleased; but he did not like it quite so much when the demon of restoration and renovation invaded his own quarters, such as the Butte des Moulins, and all that densely populated district through which the splendid Avenue de l'Opera now runs. The effect of all this was to drive the workman into the already crowded quarters at the barriers, such as La Gare, St. Lambert, Javel, and Charonne, where, according to the last statistics of theAnnuaire, the increase was at the rate of 415 per 1,000. Of course the ill health that always pervaded these quarters increased also; and, from the reports of Dr. Brouardel and M. Muller, the number of deaths from typhoid and diphtheria were doubled in ten years. Dr. Du Mesnil, in making his returns for 1881 of convalescents from typhoid, remarked that the most unsanitary arrondissements were the 4th, 11th, 15th, 18th, and 19th--precisely those to which the principal migrations of laborers had taken place. The 18th arrondissement, which in 1876 had only 601 lodging houses with 8,933 lodgers, had, in 1882, over 850, with 20,816 inmates. In the 19th arrondissement there were 517 houses in 1876, with 9,074 lodgers, and 752 in 1882, with 17,662 inhabitants.
It is not only the crowded condition of the poor quarters that is such a standing menace to the health of the city, but also the shocking state of the rooms, which the unhappy lodgers are obliged to put up with. The owners of the property are, as happens in other places besides Paris, unscrupulous and grasping to the last degree, and have not only divided and subdivided the accommodation wherever possible, but have even raised the rental in nearly all cases. Whole families are crowded into a small apartment, icy cold in winter, an oven in summer, the only air and daylight which reaches the interior coming from a window which looks on to a dirty staircase or a still fouler court reeking with sewage. There are at the present time in Paris 3,000 lodgings which have neither stove nor chimney; over 5,000 lighted only by a skylight; while in 4,282 rooms there are four children in each below 14 years of age; 7,199 with three children; and 1,049 with four beds in each. The Parisian population has augmented only 15 per cent. in seven years; but the district of poor lodging houses has increased by twenty per cent., and the number of lodgings by about 80 per cent. It is true that a law was passed in 1850 to provide for the sanitary supervision of this class of property; but in Paris the law is a dead letter, and, although it is now active in the provinces and in places like Marseilles, Lyons, Bordeaux, and Nantes, it is applied, even there, in a jerky and intermittent manner.
Perhaps the worst of the abominable dogkennels called houses was the group known as the Cité des Kroumirs, in the 13th arrondissement, which, by a strange irony, was built on land belonging to the Department of Public Assistance, which was let out by that body to a rich tenant, who sublet it to these lodging-house owners. This veritable den of infection and misery has now been demolished; but there are plenty of others quite as bad. Notably, there is the Cite Jeanne d'Arc (a poor compliment to have named it after that sturdy heroine), an enormous barrack of five stories, which contains 1,200 lodgings and 2,486 lodgers. No wonder that it was decimated in 1879 by smallpox, which committed terrible ravages here. The Cité Dore is grimly known by the poor-law doctors as the "Cemetery Gateway." The Cite Gard, in the Rue de Meaux, is inhabited by 1,700 lodgers, although it is almost in ruins. The Cite Philippe is tenanted by 70 chiffonniers, and anybody who knows what are the contents of the chiffonnier's basket, orhotte, may easily guess at the effluvia of that particular group of houses. A large lodging-house in the Rue des Boulangers is tenanted by 210 Italians, who get their living as models or itinerant musicians. Both house and tenants are declared to be unapproachable from the vermin.
It is some satisfaction to know that these houses have lately awakened the apathy of some of the public bodies, and that more than one scheme is being put forward with a view of erecting proper industrial dwellings. The Municipal Council is negotiating with the Credit Foncier for the erection of a certain number of cheap houses, which, for the space of twenty years, will be exempt from all taxes, such as octroi, highway, door and window tax, etc. There are also one or two semi-private companies, which are occupying themselves with the question, and it is to be hoped that the rumors of the pestilence in Egypt may hasten the much-needed reform.
There can be no doubt, says theEngineer, that the inventor who could supply in a really portable form a machine or apparatus that could give out two or three horse power for a day would reap an enormous fortune. Up to the present time, however, nothing of the kind has been placed in the market. Gas is laid on to most houses now, and gas engines are plenty enough, yet they do not meet the want which a storage battery may be made yet perhaps to supply.
To prove the incorrectness of Helmholtz's statement that beats do not colesce into musical sounds, but that the ear will distinguish them as a rumbling noise, even when their number rises as high as 132 vibrations per second, Rudolph Koenig has constructed a series of tuning forks, recently presented by President Morton to the Stevens Institute of Technology. The following table exhibits the number of vibrations per second of these forks, the ratios of their vibrations when two are sounded together, the number of beats produced, and the resultant sound:
On sounding two forks nearly in unison, the sound heard corresponds to a number of vibrations equal to the difference of the numbers of vibrations of the forks.
On sounding two forks, one of which is nearly the octave of the other, the ear perceives a sound, which is that given by vibrations whose number equals the difference in the number of vibrations of the higher fork and the upper octave of the lower fork.
Koenig has also found out the laws of the resultant sounds produced by other intervals than the octave, and has extended his researces to intervals differing by any number of vibrations, as may be seen from the above table.
His conclusion is that beats and resultant sounds are one and the same phenomenon.
Thus, for example, the lowest number of vibrations capable of producing a musical sound is 32 per second; in like manner, a clear musical sound is produced by two simple notes of sufficient intensity which produce 32 beats per second.
Koenig also made a very ingenious modification of the siren for the purpose of enabling Seebeck to sound simultaneously notes whose vibrations had any given ratio. It is furnished for this purpose with eight disks, each of which contains a given number of circles of holes arranged at different angular distances. A description of this instrument, which is also the property of the Stevens Institute, and of Seebeck's experiments is thus given in a letter by Koenig himself.
Effects produced when the isochronism of the shocks is not perfect.
A.
In order to produce a note, the succession of shocks must not deviate much from isochronism.
If the isochronism is but little impaired, we obtain a note corresponding to the mean interval of the shocks.
If the intervals between the shocks are alternately t and t', and if the difference between t and t' is slight, we obtain the two notes t+t' and (t+t')/2. If the intervals between the shocks are alternately t, t', and t'', we obtain the two notes t+t'+t'' and (t+t'+t")/3.
Disk No. 1 has--