Appliances for Distributing Water
We have so far discussed only the various sources of potable water. We must now turn our attention to the mechanical means for making it available for use, which comprise appliances for lifting, storing, conveying, distributing, and purifying the water.
The location of the source of supply with reference to the buildings and grounds decides generally the question whether a gravity supply is feasible or whether water must be pumped. The former is desirable because its operating expenses are almost nothing, but it is not always cheapest in first cost. Rather than have a very long line of conduit, it may be cheaper to pump water, particularly if wind or water power, costing nothing, can be used.
When it becomes necessary to pump water, there are numerous machines from which to choose; only the more important ones will be considered. We may use pumps operated by manual labor, those run by animal power, pumping machinery using the power of the wind or that of falling or running water; then there are hot-air, steam, and electric pumps, besides several forms of internal-combustion engines, such as gas, gasoline, and oil engines. Each has advantages in certain locations and under certain conditions.
Of appliances utilizing the forces of Nature, perhaps the simplest efficient machine is the hydraulic ram. While other machines for lifting water are composed of two parts, namely, a motor and a pump, the ram combines both in one apparatus. It is a self-acting pump of the impulse type, in which force is suddenly applied and discontinued, these periodical applications resulting in the lifting of water. Single-acting rams pump the water which operates them; double-acting rams utilize an impure supply to lift a pure supply from a different source.
The advantages of the ram are: it works continuously, day and night, summer and winter, with but very little attendance; no lubrication is required, repairs are few, the first cost of installation is small. Frost protection, however, is essential. The disadvantages are that a ram can be used only where a large volume of water is available. The correct setting up is important, also the proper proportioning in size and length of drive and discharge pipes. The continual jarring tends to strain the pipes, joints, and valves; hence, heavy piping and fittings are necessary. A ram of the improved type raises water from twenty-five to thirty feet for every foot of fall in the drive pipe, and its efficiency is from seventy to eighty per cent.
Running water is a most convenient and cheap power, which is often utilized in water wheels and turbines. These supply power to run a pump; the water to be raised may come from any source, and the pump may be placed at some distance from the water wheel. Where sufficient fall is available—at least three feet—the overshot wheel is used. In California and some other Western States an impulse water wheel is much used, which is especially adapted to high heads.
The power of the wind applied to a windmill is much used for driving pumps. It is a long step forward from the ancient and picturesque Dutch form of windmill, consisting of only four arms with cloth sails, to the modern improved forms of wheels constructed in wood and in iron, with a large number of impulse blades, and provided with devices regulating the speed, turning the wheel out of the wind during a gale, and stopping it automatically when the storage tank is filled. The useful power developed by windmills when pumping water in a moderate wind, say of sixteen miles an hour velocity, is not very high, ranging from one twenty-fifth horse-power for an eight and one-half foot wheel to one and one-half horse-power for a twenty-five foot wheel. The claims of some makers of windmills as to the power developed should be accepted with caution.
The chief advantage is that, like a ram, the windmill may work night and day, with but slight attention to lubrication, so long as the wind blows. But there are also drawbacks; it requires very large storage tanks to provide for periods of calm; the wheel must be placed sufficiently exposed to receive the full wind force, either on a tower or on a high hill, and usually this is not the best place to find water. Besides, a windmill tower, at least the modern one, is not an ornamental feature in the landscape. It is expensive when built sufficiently strong to withstand severe winter gales. During the hot months of the year, when the farmer, the gardener, and the coachman require most water, the wind is apt to fail entirely for days in succession.
If water is not available, and wind is considered too unreliable, pumping must be accomplished by using an engine which, no matter of what form or type, derives its energy from the combustion of fuel, be the same coal, wood, charcoal, petroleum or kerosene, gas, gasoline, or naphtha. The use of such pumping engines implies a constant expense for fuel, operation, maintenance, and repairs. In some modern forms of engines this expense is small, notably so in the oil engine,and also in the gasoline engine; hence these types have become favorites.
An advantage common to all pumping engines is that they can be run at any time, not like the windmill, which does not operate in a light breeze, nor like the ram, which fails when the brook runs low. Domestic pumping engines are built as simple as possible, so that the gardener, a farm hand, or the domestic help may run them. Skill is not required to operate them, and they are constructed so as to be safe, provided ordinary intelligence is applied.
In using a fuel engine it is desirable, because of the attendance required, to take a machine of such capacity and size that the water supply required for two or three days may be pumped to the storage tank in a few hours.
A favorite and extensively used type of domestic pump is the hot-air engine, in which the expansive force of heated air is used to do useful work. Among the types are simple and safe machines which do not easily get out of order. They are started by hand by giving the fly wheel one or more revolutions. If properly taken care of they are durable and do not require expensive repairs.
In gas engines power is derived from the explosion of a mixture of gas and air. Where a gas supply is available, such engines are very convenient, for, once started, they will run for hours without attention. They are economical in the consumption of gas, and give trouble only where the quality of gas varies.
Owing to the unavailability of gas on the farm and in country houses, two other forms of pumping engines have been devised which are becoming exceedingly popular. One is the gasoline, the other is the oil engine. Both resemble the gas engine, but differ from it in using a liquid fuel which is volatilized by a sprayer. Gasoline engines are now brought to a high state of perfection.
In recent years, internal-combustion engines which use heavy kerosene or crude oil as fuel have been introduced. These have two palpable advantages: first, they are safer than gasoline engines; second, they cost less to run, for crude oil and even refined kerosene are much cheaper than gasoline. Oil engines resemble the gas and gasoline engines, but they have larger cylinders, because the mean effective pressure evolved from the explosion is much less than that of the gasoline engines.
Oil engines for pumping water are particularly suitable in regions where coal and wood cannot be obtained except at exorbitant cost. Usually, the engine is so built as to be adapted for other farm work. It shares this advantage with the gasoline engine. Oil engines are simple, reliable, almost automatic, compact, and reasonable in first cost and in cost of repairs. There are many forms of such engines in the market. To be successful from a commercial point of view, an oil engine should be so designed and built that any unskilled attendant can run, adjust, and clean it. The cost of operating them, at eight cents per gallon for kerosene, is only one cent per hour per horse-power; or one-half of this when ordinary crude oil is used. The only attention required when running is periodical lubrication and occasional replenishing of the oil reservoir. The noise of the exhaust, common to all engines using an explosive force, can be largely done away with by using a muffler or a silencer. The smell of oil from the exhaust likewise forms an objection, but can be overcome by the use of an exhaust washer.
The well-known forms of steam-pumping engines need not be considered in detail, because high-pressure steam is not often available in country houses. Where electric current is brought to the building, or generated for lighting purposes, water may be pumpedby an electric pump. Electric motors are easy and convenient to run, very clean, but so far not very economical. Electric pumps may be arranged so as to start and stop entirely automatically. Water may be pumped, where electricity forms the power, either by triplex plunger pumps or by rotary, screw, or centrifugal pumps.
Space forbids giving a description of the many simpler devices used for lifting water. In small farmhouses lift and force pumps worked by hand are now introduced, and the old-fashioned, moss-covered draw-bucket, which is neither convenient nor sanitary, is becoming a relic of past times.
The water pumped is stored either in small masonry or earth reservoirs, or else in storage tanks of either wood, iron, or steel, placed on a wood or steel tower. Wooden tanks are cheap but unsightly, require frequent renewal of the paint, and give trouble by leaking, freezing, and corrosion of hoops. In recent years elevated tanks are supplanted by pressure tanks. Several such systems, differing but little from one another, are becoming quite well known. In these water is stored under suitable pressure in air-tight tanks, filled partly with water and partly with air.
One system consists of a circular, wrought-steel, closed tank, made air- and water-tight, a force pump for pumping water into the tank, and pipe connections. The tank is placed either horizontally or vertically in the basement or cellar, or else placed outdoors in the ground at a depth below freezing. Water is pumped into the bottom of the tank, whereby its air acquires sufficient pressure to force water to the upper floors.
This simple system has some marked advantages over the outside or the attic tank. In these, water gets warm in summer and freezes in winter. Vermin and dust get into the tank, and the water stagnates. In the pressure tank, water is kept aërated, cool, and clean.
Another pressure tank has an automatic valve, controlled by a float and connected with suction of pump. It prevents the tank from becoming water-logged by maintaining the correct amount of air inside.
Still another system using pressure tanks is more complete than either of the others, comprising engine, pump, air compressor, a water tank, and also an air tank. It is best described by a recent example constructed from plans and under the direction of the writer. The buildings supplied with water comprise the mansion, the stable, the cottage, and a dairy, andthe pumping station is placed near the shore of the lake from which the supply is taken. See Figs.1and2.
Fig. 1.Fig. 1.VIEW FULL SIZEDIAGRAM OF COMPRESSED AIR TANK SYSTEM.
DIAGRAM OF COMPRESSED AIR TANK SYSTEM.
Fig. 2.Fig. 2.PRESSURE-TANK PUMPING STATION.Interior view of pumping station of compressed air-tank system (seeplanon opposite page) showing 3,000 gallon water tank, air tank of 150 pounds pressure and 10 horse-power gasoline engine.
PRESSURE-TANK PUMPING STATION.
Interior view of pumping station of compressed air-tank system (seeplanon opposite page) showing 3,000 gallon water tank, air tank of 150 pounds pressure and 10 horse-power gasoline engine.
The pump house is about 20 feet by 27 feet, and contains a water-storage tank 6 feet in diameter and 131/2feet long, of a capacity of 3,000 gallons; an air tank of same dimensions as the water tank, holding air under 150 pounds pressure; a 10 horse-power gasoline engine, direct-connected, by means of friction clutch,with an air compressor and also with a triplex pump of 75 gallons capacity per minute.
The water in the tank is kept under 75 pounds pressure, and at the hydrant near the house, located about 100 feet above the pumping station, there is an available pressure of 33 pounds. The last drop of water flows from the water tank under the full pressure of 75 pounds at the pumping station. The suction pipe into the lake is 4 inches and is provided with well strainers to prevent clogging.
The cost of pumping water by this system is quite reasonable. The gasoline engine requires per horse-power per hour about 11/4gallons of gasoline, and at sixteen cents per gallon this makes the cost for 1,000 gallons pumped about five cents. To this expense should, however, be added the cost of lubricating oil, repairs, amount for depreciation, and the small cost for labor in running the engine.
Water pipes forming a distribution system should always be chosen generous in diameter, in order to avoid undue loss of pressure by friction. Where fire hydrants are provided, the size of the water main should not be below four inches. All branches should be controlled by shut-offs, for which the full-way gate valves are used in preference to globe valves. Pipe-line material is usually galvanized, screw-jointed wrought iron for sizes up to four inches.
In conclusion, a word about water purification. Where the quality of the water supply is not abovesuspicion it may be improved by filtration. A filter should never be installed without the advice of a qualified expert, for there are numerous worthless devices and few really efficient ones. Where a filter is not available, the water used for drinking should be boiled or sterilized if there is the slightest doubt as to its wholesomeness.
Purifying Water by Copper Sulphate
From the standpoint of the health of the community, the most vital problem is to get pure water. Almost equally important, when comfort and peace of mind is considered, is the procuring of sweet water. The wise owner of a country home looks to the water supply upon which his family is dependent. The careful farmer is particular about the water his stock, as well as his family, must drink. But careless persons constitute the large majority. Most people in the city and in the country pay no attention to their drinking water so long as it "tastes all right."
Some years ago the inhabitants of Ithaca, N. Y., furnished a pitiful example of this foolhardy spirit. For a year previous to the breaking out of the typhoid epidemic, the public was warned, through the local and the metropolitan press, of the dangerous condition of Ithaca's water supply. Professors of Cornell College joined in these warnings. But the people gave no heed, probably because the water wasclearand its taste sweet and agreeable. As was the case in this instance,bacteria are tolerated indefinitely, and it is only an alarming increase in the death rate that makes people careful. Then they begin to boil the water—when it is too late for some of them.
But let the taste become bad and the odor repulsive, and a scare is easily started. "There must be dead things in the water, or it wouldn't taste so horrible," is the common verdict. Some newspaper seizes upon the trouble and makes of it a sensation. The ubiquitous reporter writes of one of "the animals" that it "looks like a wagon wheel and tastes like a fish." With such a remarkable organism contaminating one's drink no wonder there is fear of some dread disease. The water is believed to be full of "germs"; whereas the pollution is entirely due to the presence of algæ—never poisonous to mankind, in some cases acting as purifying agents, but at certain seasons of the year imparting a taste and odor to the water that cannot be tolerated.
Algæ—what are they? They are aquatic plants. Algæ are not to be confounded with the water vegetation common to the eye and passing by the term weeds. Such plants include eelgrass, pickerel weed, water plantain, and "duckmeat"—all of which have roots and produce flowers. This vegetation does not lend a bad odor or taste to the water. In itself it is harmless, although it sometimes affords a refuge for organisms of a virulent type.
But when the aquatic vegetation of the flowering variety is eliminated from consideration, there still remains a group of water plants called algæ. They comprise one-fifth of the known flowerless plants. They are the ancestors of the entire vegetable kingdom. Those whose habitat is the sea number the largest plants known in nature. Certain forms found in the Pacific are supposed to be 800 feet in length; others are reported to be 1,500 feet long. The marine variety are familiar as the brown kelps and the wracks, which are very common along our Northern coast.
The fresh-water algæ are usually grass green in color. This green variety is often seen as a spongy coating to the surface of stagnant pools, which goes by the name of "frog spawn" or "pond scum." One of this description,Spirogyra, has done thousands of dollars' worth of damage by smothering the life out of young water-cress plants in artificial beds constructed for winter propagation. When the cress is cut the plants are necessarily left in a weakened condition, and the algæ form a thick mat over the surface of the water, thus preventing the growth of the cress plants and oftentimes killing them. The absolute necessity of exterminating these algæ led to the perfection of the copper-purification process.
It is, however, a variety of algæ not easily detected that contaminates the water. So long as they are in a live, healthy condition they benefit drinking water by purifying it. Indeed, some scientists have attributed the so-called self-purification of a stream entirely to the activities of these plants. Of such, one form,Chlamydomonas, is bright grass green in appearance. But the largest group—the plants which have the worst reputation as polluters of drinking water—are popularly known as the "blue-green algæ" (Schizophyceæ). The common name tells the color of these plants, although there are exceptions in this respect, some of them showing shades of yellow, brown, olive, chocolate, and purplish red. This variety of algæ flourishes in the summer months, since a relatively high temperature and shallow stagnant water favor its germination. If the pond begins to dry up, the death of the organisms takes place, and the result is a most disagreeable, persistent odor which renders the water unfit for drinking purposes. This result is chemically due to the breaking down of highly organized compounds of sulphur and phosphorus in the presence of the large amount of nitrogen contained in these plants. Decomposition is not necessary for some of the blue greens to give off a bad odor, however. A number of them, on account of their oil-content, produce an odor when in a healthy condition that is sometimes likened to raw green corn or to nasturtiums, but usually it cannot be so pleasantly described.
The Department of Agriculture has been able to solve the problem of exterminating algæ from water supplies.[1]The department has done more; for it has succeeded in perfecting a method by which a reservoir contaminated with typhoid or other pathogenic bacteria can be purified. The work was begun with an inquiry into the extent of the trouble from algal pollution. Letters were addressed to some five hundred engineers and superintendents of water companies scattered all over the United States. The replies, which came from almost every State in the Union, were burdened with one complaint—"Algæ are our worst pest"; and with one prayer—"Come over into Macedonia, and help us."
Convinced of the need of earnest work, extensive laboratory experiments were inaugurated. The problem presented was this: the remedy must not only be readily available, but it must be cheap, that advantage may be taken of it by the poorest communities, as well as by those owning large reservoirs. Above all, the remedy must be absolutely harmless to man; the poison used to exterminate algæ must not in any way affect the water drinkers. A large number of substances were used in the experiments before the final decision rested with copper sulphate. This salt is very poisonous to algæ. On the other hand, copper in solution just strong enough to destroy algal growth could not possibly injure man; in fact, the temporary presence of such a small amount of copper in drinking water could not be detected.
The results in the laboratory being successful, the next step was to make a practical demonstration of the value of the method. This was first done in the fall of 1901. At Ben, Va., water cress is grown in large quantities during the winter, when it is a valuable market crop. Dams are constructed across a stream in such a manner as to enable the maintenance of a water level not too high for the growth of plants; when a freeze is threatened the plants can be flooded. In the cress beds selected for the experiments the water is obtained from a thermal spring whose temperature throughout the year is about 70° F. This temperature is particularly favorable to the growth of "frog spawn." After the cress was cut for market, the algæ frequently developed so rapidly as to smother the life out of the weakened plants. When this occurred, the practice was to rake out both water cress and algæ and reset the entire bed. This was not only expensive; half the time it failed to exterminate the pest. It was,therefore, most desirable to devise a method of ridding the bed of algal growth without injuring the cress.
Here the copper-sulphate method was put to a practical test. At the outset a strong solution was sprayed on the algæ which coated the surface of the pond. This only killed the algal growth with which the particles of copper came in contact and left the main body of algæ unaffected. Then trial was made of dissolving the copper directly in the water, and the result was most satisfactory. The solution used was that of 1 part of copper to 50,000,000 parts of water.
Growers need have no trouble in the future. They need have no fear of employing the method, as the copper solution required for killing the algæ could not possibly injure water cress, provided ordinary care is used in the work. As to the frequency of treatment required, one or two applications a year will generally be found sufficient, as this letter, received from the manager of the Virginia company, goes to show:
"The 'moss' has given me no trouble at all this winter; in fact, I have for six months had to resort to the copper sulphate only once.... All the conditions were favorable last fall and early winter for a riot of 'moss,' but it did not appear at all until just a few days ago, and then yielded to treatment much more readily than it did when I first began to use thecopper." This letter was written over three years after Dr. Moore made his experiment in these cress beds.
Satisfied with the results attained in exterminating algal growth in water-cress beds, attention was next given to reservoirs. Some fifty water supplies were treated during the summer of 1904, and in every case success attended the copper cure. In one respect the results were surprising. It was found that in practice the copper-sulphate method worked better than in theoretic experimentation; results in large reservoirs were more pronounced than in the laboratory. In fact, it developed that the solution necessary to kill algæ in the laboratory must contain from five to twenty times as much copper as that contained in a solution which will exterminate algal growth in its natural habitat. This is not easily explained, if it can be explained at all. The test reason advanced is that only the most resistant organisms stand transplanting to an artificial environment. But, after all, the important point is that the new method works better in practice than was expected.
Thus the department is able to announce that the process is no longer in the experimental stage, and also to say what conditions must be known in determining the proper quantity of copper sulphate for destroying algæ, together with a prescription for the copper cure.Here it is, for the benefit of careful persons who will use the method with proper intelligence: "The importance of knowing the temperature of the contaminated water is second only to the necessity of knowing the organism present. With increase of temperature the toxicity of a given dilution increases, andvice versa. Assuming that 59° F. is the average temperature of reservoirs during the seasons when treatment is demanded, the quantity of copper should be increased or decreased approximately 2.5 per cent for each degree below or above 59° F.
"Similar scales should be arranged for the organic content and the temporary hardness of the water. With the limited data at hand it is impracticable to determine these figures, but an increase of 2 per cent in the quantity of copper for each part per 100,000 of organic matter and an increase of 0.5 to 5 per cent in the proportion of copper for each part per 100,000 of temporary hardness will possibly be found correct. The proper variation in the increase due to hardness will depend upon the amount of dissolved carbon dioxide; if very small, 5 per cent increase is desirable; if large, 0.5 per cent is sufficient."
The information in this prescription is to be used in connection with a table[2]published by the Department of Agriculture. This table gives the number of parts of water to one part of copper sulphate necessary to kill the various forms of algæ which are listed. Theformulæ vary from 1 part of copper to 100,000 parts of water, necessary to destroy the most resistant and very rare forms (three of these are listed), to 1 part of copper in 25,000,000 parts of water, which is a sufficiently strong solution to exterminateSpirogyra, the cress-bed pest. By far the majority of forms do not require a solution stronger than that of 1 part of copper to 1,000,000 parts of water.
It is true that the department is not now holding out, directly, a helping hand to the owner of a country place, or to the farmer, in this campaign of purifying drinking water. In the first place, the greatest good of the greatest number demands that large reservoirs, which supply a great number of people with drinking water, ought to be considered first. Such supplies, moreover, are most frequently contaminated. Where fifty reservoirs were treated last summer, ten times that number will be "cured" this summer. It will be readily seen, therefore, that in conducting such a large number of experiments—considering preliminary reports, prescribing for treatment, and keeping proper account of results—the department, with a limited force and limited facilities, has its hands more than full.
More important still, there is an absolute need of the services of some expert on the ground. While analgologist is a functionary not generally employed by water companies—in fact, a man trained in the physiology of algæ is difficult to find—nevertheless, it is highly important, as the department views it, to have the coöperation of an expert versed to some extent in the biological examination of drinking water. In other words, the copper cure is not a "patent medicine," with printed directions which any person could follow. Intelligence and care are absolutely essential in the use of this treatment. Furthermore, each case must be treated as a distinct and separate case, as a physician would treat a patient.
Suppose, however, an owner of a country place, which is dependent upon a fresh-water pond for its water supply, finds that his drinking water is contaminated, that the taste and odor are such as to render the water unfit for use. There is no reason why he should not treat the supply, provided he is properly careful. When the nature of the polluting organism is definitely determined and the average temperature of the water observed, then the necessary formula can be decided upon. First, of course, the pond must be plotted, the depth found, and the capacity computed. The department will willingly furnish data for this purpose, together with blanks upon which to submit details as to contaminating organisms and water temperature, to any applicant. Once the proper solution is determined upon, the actual work of purification is most simple. In the following directions the department outlines the most practicable method of introducing the copper sulphate into a water supply:
"Place the required number of pounds of copper sulphate in a coarse bag—gunny sack or some equally loose mesh—and, attaching this to the stern of a row-boat near the surface of the water, row slowly back and forth over the reservoir, on each trip keeping the boat within ten to twenty feet of the previous path. In this manner about a hundred pounds of copper sulphate can be distributed in one hour. By increasing the number of boats, and, in the case of deep reservoirs, hanging two or three bags to each boat, the treatment of even a large reservoir may be accomplished in from four to six hours. It is necessary, of course, to reduce as much as possible the time required for applying the copper, so that for immense supplies, with a capacity of several billion gallons, it would probably be desirable to use a launch, carrying long projecting spars to which could be attached bags containing several hundred pounds of copper sulphate.
"The substitution of wire netting for the gunny-sack bag allows a more rapid solution of the sulphate, and the time required for the introduction of the saltmay thus be considerably reduced. It is best to select as warm a day for treatment as circumstances will permit."
Not difficult, one would say. No—when the proper solution is determined; to reach that determination is the difficulty. That the method can be tried "at home" is proved by the results obtained by the owner of a country home in the vicinity of New York. Tired of consulting engineers, who looked at his water supply, informed him that they could do nothing, and then charged him a big fee (to one he paid $250), this owner resorted to the copper-sulphate treatment. The cure cost the man just $2—but let his letter to the department tell the story:
"My place in the country is located at Water Mill, in the township of Southampton, in Long Island. I purchased it in April, 1902, and was largely influenced in selecting this piece of land by the beauty of a pond which bounds it on the east. This little body of water covers about two acres, is fed by numerous springs, and discharges into Mecox Bay, the southern boundary of the land. When I bought the place the pond was filled with clear water. About the middle of the following June algæ began to show, and in August the surface was almost entirely covered by the growth. The odor was offensive, and myriads of small insects hovered over the masses of algæ much of the time.I consulted two engineers interested in the storage of water, and they told me that nothing could be done. The condition was so objectionable that I planned to plant a thick hedge of willows along the bank to shut off the view of the pond from the house.... I examined the pond on June 15th and found large masses of algæ covering an area several hundred feet in length and from twenty to forty feet in width. No microscopical examination was made of the growth, but I was informed that it seemed to be largely composed of filaments ofSpirogyraand otherConfervæ. On June 18th the treatment was begun.... In one week the growth had sunk and the pond was clear water. I examined the pond September 15th and found it still clear.
"The use of the sulphate of copper converted an offensive insect-breeding pond into a body of beautifully clear water. The pond was full of fish, but the copper did not seem to harm them."
Native trout were not injured when the large reservoir at Cambridge, N. Y., was purified by the copper treatment. A slightly different result, in this respect, was reported from Elmira, N. Y., however. Part of the report is as follows:
"The effect of the copper-sulphate treatment on the different animal life was as follows: numerous 'pollywogs' killed, but no frogs; numerous small (less than two inches long) black bass and two large ones (eight inches long) killed; about ten large 'bullheads' were killed, but no small ones; numerous small (less than two inches long) 'sunfish' were killed, but no large ones.
"The wind brought the dead fish to the corners of the reservoir, and it was very little trouble to remove them. No dead fish were seen twenty-four hours after completion of the treatment."
The injury done by copper sulphate to fish is a more serious matter than was at first supposed. Brook trout are, apparently, the least resistant to the salt. A Massachusetts trout pond stocked with eight-inch trout lost forty per cent as a result of the introduction of a strong solution of copper sulphate. The Bureau of Fisheries is working in conjunction with the Division of Plant Physiology in this matter, and it is hoped to secure reliable information. In the meantime, owners of ponds stocked with game fish would do well to take great care before resorting to the copper cure for algæ—that is, if they hesitate to lose a part of the fish.
When a pond or reservoir is treated with the proper amount of copper sulphate to remove algæ—except in the case of the few very resistant forms requiring a stronger solution than 1 part of copper to 1,000,000parts of water—there is no need of discontinuing the use of the water supply during treatment; the water may be drunk with impunity. But when water known to be polluted with pathogenic bacteria is sterilized by means of copper sulphate in strong solution, it is just as well to discontinue the use of the water for drinking purposes for not more than twenty-four hours. Even then, this is an overcareful precaution rather than a necessity.
Experiments conducted with great care and thoroughness demonstrate that at room temperature, which is near the temperature of a reservoir in summer, a solution of 1 part of copper to 100,000 parts of water will destroy typhoid bacteria in from three to five hours. Similar experiments have proved that a copper solution of like strength is fatal to cholera germs in three hours, provided the temperature is above 20° F. As was the case with algæ, bacteria were found to be much more sensitive to copper when polluting water than when grown in artificial media.
The toxic effect of metallic copper upon typhoid bacteria in water gives some hints as to prevention of the disease by the use of copper tanks. This should not altogether take the place of the boiling of the water; it is useful in keeping it free from contamination, although water allowed to stand in copper receptacles for a period of from twenty-four to forty-eight hours at room temperature would be effectively sterilized, no matter what its contamination and no matter how much matter it held in suspension. But in order to insure such results the copper must be kept thoroughly clean. This polishing is not, as was popularly supposed, to protect the consumer from "copper poisoning," but to prevent the metal from becoming so coated with foreign substances that there is no contact of the copper with the water, hence no antiseptic quality.
Dr. Henry Kreamer, of Philadelphia, proved that within four hours typhoid germs were completely destroyed by the introduction into the polluted water of copper foil.
"Granting the efficiency of the boiling of water for domestic purposes, I believe that the copper-treated water is more natural and more healthful.... The intestinal bacteria, like colon and typhoid, are completely destroyed by placing clean copper foil in the water containing them.
"Pending the introduction of the copper treatment of water on a large scale, the householder may avail himself of a method for the purification of drinking water by the use of strips of copper foil about three and one-half inches square to each quart of water, this being allowed to stand overnight, or from six to eight hours at the ordinary temperature, and then the water drawn off or the copper foil removed."
Although a splendid antiseptic, copper in weak solution is not harmful, no more so than the old copper utensils used by our forefathers were harmful. Undoubtedly they were of benefit, and the use of them prevented the growth of typhoid and other bacteria. People of to-day might well go back to copper receptacles for drinking water.
FOOTNOTES:[1]For published reports of the work, see Bulletins 64 and 76, Bureau of Plant Industry, U. S. Department of Agriculture; reports prepared by Dr. George T. Moore and his assistant, Mr. Karl F. Kellerman.[2]See Bulletin No. 76, supra.
[1]For published reports of the work, see Bulletins 64 and 76, Bureau of Plant Industry, U. S. Department of Agriculture; reports prepared by Dr. George T. Moore and his assistant, Mr. Karl F. Kellerman.
[1]For published reports of the work, see Bulletins 64 and 76, Bureau of Plant Industry, U. S. Department of Agriculture; reports prepared by Dr. George T. Moore and his assistant, Mr. Karl F. Kellerman.
[2]See Bulletin No. 76, supra.
[2]See Bulletin No. 76, supra.
Ridding Stagnant Water of Mosquitoes
Because of the serious and often fatal injury it inflicts on man, the most dangerous animal known is the mosquito. Compared with the evil done by the insect pest, the cobra's death toll is small. This venomous serpent is found only in hot countries, particularly in India, while mosquitoes know no favorite land or clime—unless it be Jersey. Arctic explorers complain of them. In Alaska, it is recorded by a scientist that "mosquitoes existed in countless millions, driving us to the verge of suicide or insanity." A traveler on the north shore of Lake Superior, when the snow was several feet deep, and the ice on the lake five feet in thickness, relates that "mosquitoes appeared in swarms, literally blackening the banks of snow in sheltered places."
In the temperate zone this evil-breeding insect was, until recent years, considered more in the light of an exasperating pest. It is now known, however, thatmalaria is due entirely to the bites of mosquitoes. But it is in the tropical countries that their deadliest work is done. There, it has been proved beyond question, the mosquitoes are responsible for the carriage of yellow fever. If, in a yellow-fever ridden region, one were to live entirely in an inclosure, carefully protected with proper screens—as certain entomologists did—there practically would be no danger from the dread disease, even if all other precautions were neglected.
The crime committed by the mosquito against its innocent victim, man, is more in the nature of manslaughter than of murder, according to the authorities. There is nopremeditated malice. "A mosquito bites primarily to obtain food," says a leading entomologist; "there is neither malice nor venom in the intent, whatever there may be in the act." There isn't great comfort in the intelligence conveyed by the scientist, nor in his further observation:
"Theoretically, there would seem to be no reason why there should be any pain from the introduction of the minute lancets of the insects, and the small amount of bloodletting is usually a benefit rather than otherwise. Unfortunately, however, in its normal condition the human blood is too much inclined to clot to be taken unchanged into the mosquito stomach;hence, when the insect bites, a minute droplet of poison is introduced, whose function it is to thin out the fluid and make it more suitable for mosquito digestion. It is this poison that sets up the inflammation and produces the irritation or swelling.... The pain is caused entirely by the action of the poison in breaking up the blood, and, as the first act of a biting mosquito is to introduce the poison into the wound, the pain and inflammation will be the same, whether the insect gets its meal or not. In fact, it has been said that if a mosquito be allowed to suck its fill and then fly, the bite will not itch, and there is just a basis of justification for this."
To make a scientific inquiry into the habits of the mosquito, and to do it patiently, one should be far from the maddening swarms, or at least effectively screened in. Then it would be possible to believe the statement of the Government's entomologist that not "one mosquito in a million" ever gets the opportunity to taste the blood of a warm-blooded animal. As proof of this there are, in this country, great tracts of marshy land never frequented by warm-blooded animals, and in which mosquitoes are breeding in countless numbers. The point is emphasized by the prevalence of mosquitoes in the arctic circle and other uninhabited regions.
If this gory insect does not live by blood alone, how is it nourished? Female mosquitoes are by nature vegetarians; they are plant feeders. Why they shoulddraw blood at all is a question which remains unsolved by entomologists—as well as by the suffering victims. The females have been observed sucking the nectar from flowers; obtaining nutriment from boiled potatoes, even from watermelon rinds, from which they extract the juice. As regards the blood habit, the male mosquito is a "teetotaler." Just how this male insect lives, scientists have not determined. He may not take nourishment at all. At any rate, the mouth parts of the male are so different from those of the female that it is probable his food is obtained differently. The male is often seen sipping at drops of water, and a taste for molasses is ascribed to the male mosquito by one authority.
A common remark heard along the Jersey shore, also on Long Island, is this: "When we have a sea breeze we are not troubled with mosquitoes, but when there comes a land breeze they are a pest." While this observation is true, the reasons therefore entertained by the unscientific mind are erroneous. The matter of the absence or abundance of mosquitoes in varying winds is closely related to the inquiry which entomologists have made: how far will mosquitoes fly? Says one investigator:
"The migration of mosquitoes has been the source of much misapprehension on the part of the public.The idea prevalent at our seaside resorts that a land breeze brings swarms of mosquitoes from far inland is based on the supposition that these insects are capable of long-sustained flight, and a certain amount of battling against the wind. This is an error. Mosquitoes are frail of wing; a light puff of breath will illustrate this by hurling the helpless creature away, and it will not venture on the wing again for some time after finding a safe harbor. The prevalence of mosquitoes during a land breeze is easily explained. It is usually only during the lulls in the wind that Culex can fly. Generally on our coast a sea breeze means a stiff breeze, and during these mosquitoes will be found hovering on the leeward side of houses, sand dunes, and thick foliage.... While the strong breezes last, they will stick closely to these friendly shelters, though a cluster of houses may be but a few rods off, filled with unsuspecting mortals who imagine their tormentors are far inland over the salt meadows. But if the wind dies down, as it usually does when veering, out come swarms upon swarms of females intent upon satisfying their depraved taste for blood. This explains why they appear on the field of action almost immediately after the cessation of the strong breeze; on the supposition that they were blown inland, this sudden reappearance would be unaccountable."
A sultry, rainy period of midsummer is commonly referred to as "good mosquito weather." The accepted idea is that mosquitoes are much more abundant at such times. This is true, and the explanation is simple. Mosquito larvæ, or wrigglers, as they are termed, require water for their development. A heavy shower leaves standing water, which, when the air is full of moisture, evaporates slowly. Then, too, the heat favors the growth of the microörganisms on which the larvæ feed; wrigglers found in the water forty-eight hours after their formation will have plenty of food, and adult mosquitoes will appear six to eight days after the eggs are laid. Clear weather, with quick evaporation, interferes with the development of the wrigglers, so that a season with plenty of rain, but with sunshiny, drying weather intervening, is not "good mosquito weather."
Inasmuch as a generation of mosquitoes appear to torment man within ten days, at the longest, after the eggs are laid; as a batch laid by a female mosquito contains from two hundred to four hundred eggs; as from each egg may issue a larva or wriggler which in six days will be an adult mosquito on the wing—it is to the destruction of the larvæ that attention should be directed. The larva is a slender organism, white or gray in color, comprising eight segments. The last of these parts is in the form of a tube, through which the wriggler breathes. Although its habitat is thewater, it must come to the surface to breathe, therefore its natural position is head down and tail, or respiratory tube, up. Now, if oil is spread on the surface of a pool inhabited by mosquito larvæ, the wrigglers are denied access to the air which they must have. Therefore, they drown, just as any other air-breathing animal would drown under similar circumstances.
As to the best methods to employ in ridding a country place, or any other region, of mosquitoes, the directions furnished by Dr. L. O. Howard, the Government entomologist, who has been a careful student of the problem since 1867, are of great value:
"Altogether,[3]the most satisfactory ways of fighting mosquitoes are those which result in the destruction of the larvæ or the abolition of their breeding places. In not every locality are these measures feasible, but in many places there is absolutely no necessity for the mosquito annoyance. The three main preventive measures are the draining of breeding places, the introduction of small fish into fishless breeding places, and the treatment of such pools with kerosene. These are three alternatives, any one of which will be efficacious and any one of which may be used where there are reasons against the trial of the others."
"The quantity of kerosene to be practically used, as shown by the writer's experiments, is approximately one ounce to fifteen square feet of water surface, and ordinarily the application need not be renewed for one month.... The writer is now advising the use of the grade known as lubricating oil, as the result of the extensive experiments made on Staten Island. It is much more persistent than the ordinary illuminating oils.... On ponds of any size the quickest and most perfect method of forming a film of kerosene will be to spray the oil over the surface of the water.... It is not, however, the great sea marshes along the coast, where mosquitoes breed in countless numbers, which we can expect to treat by this method, but the inland places, where the mosquito supply is derived from comparatively small swamps and circumscribed pools. In most localities people endure the torment or direct their remedies against the adult insect only, without the slightest attempt to investigate the source of the supply, when the very first step should be the undertaking of such an investigation.
"The remedy which depends upon draining breeding places needs no extended discussion. Naturally the draining off of the water of pools will prevent mosquitoes from breeding there, and the possibility of such draining and the means by which it may be done will vary with each individual case. The writer is informed that an elaborate bit of work which has been done at Virginia Beach bears on this method. Behind the hotels at this place, the hotels themselves fronting upon the beach, was a large fresh-water lake, which, with its adjoining swamps, was a source of mosquito supply, and it was further feared that it made the neighborhood malarious. Two canals were cut from the lake to the ocean, and by means of machinery the water of the lake was changed from a body of fresh to a body of salt water. Water that is somewhat brackish will support mosquitoes, but water that is purely salt will destroy them."
"The introduction of fish into fishless breeding places is another matter. It may be undesirable to treat certain breeding places with kerosene, as, for instance, water which is intended for drinking, although this has been done without harm in tanks where, as is customary, the drinking supply is drawn from the bottom of the tank. The value of most small fishes for the purpose of destroying mosquito larvæ was well indicated by an experience described to us by Mr. C. H. Russell, of Bridgeport, Conn. In this case a very high tide broke away a dike and flooded the salt meadows of Stratford, a small town a few miles from Bridgeport. The receding tide left two small lakes, nearly side by side and of the same size.In one lake the tide left a dozen or more small fishes, while the other was fishless. An examination by Mr. Russell in the summer of 1891 showed that while the fishless lake contained tens of thousands of mosquito larvæ, that containing the fish had no larvæ. The use of carp for this purpose has been demonstrated, but most small fish will answer as well. The writer knows of none that will be better than either of the common little sticklebacks (Gasterosteus aculeatusorPygosteus pungitius)."
Is mosquito fighting a success? This question is an all-important one, not only to the summer resident, but also to cities and towns contiguous to salt-water marshes, or to swampy lands, well suited for mosquito breeding. The answer is this: Mosquito control is possible; actual extermination impossible with an insect that develops so rapidly. The "Jersey mosquito," the unscientific name popularly given to an insect of huge size and ravenous appetite, has become famous. As a matter of fact, the species of mosquitoes found in New Jersey are no more rare or varied than those found on Staten Island or on Long Island. But until very recently the region lying between Jersey City and Newark has been particularly favorable to the development of mosquito larvæ. It has been announced in the press that mosquitoes have been driven out of the Newark meadows. This is an exaggeration, of course, but the work accomplished there is remarkable, and other infected regions may take heart from themarked success which has attended the efforts of Dr. John B. Smith, Entomologist of the New Jersey State Agricultural Experiment Station.
The salt marsh lying within the limits of the city of Newark covers an area of about 3,500 acres. It extends from a point on the Passaic River to the mouth of Bound Creek, where it empties into Newark Bay. Its length is about eight miles and it has an extreme width of three miles. The Newark marsh problem was a very complex one. The meadows are cut into many sections by the several traversing railroads and by creeks; this materially influences the drainage. The Peddie Street sewer crosses the marsh in a straight line of about three miles from the city to the bay. This sewer is twenty feet wide, and its banks are from three to four feet above the marsh land.
An experiment with machine ditching was made in 1903. The worst parts of the marsh were selected, and about 40,000 feet of ditches were cut. These ditches were six inches wide, two feet deep, and the drainage was perfect from the outset. The section of meadow thus drained became so dry in consequence that the grass growing there can now be cut by a machine in summer, whereas formerly the hay could be mown only in winter. The work was so successful that the Newark Common Council appropriated $5,000to complete the mosquito drainage of the marsh. Of the results obtained up to this spring, Dr. Smith says:
"This Newark marsh problem was an unusual one, and one that would not be likely to recur in the same way at any other point along the coast. Nevertheless, of the entire 3,500 acres of marsh, not 100 acres remain on which there is any breeding whatever, and that is dangerous only in a few places and under certain abnormal conditions. Including old ditches cleaned out, about 360,000 running feet of ditches have been dug on the Newark marshes, partly by machine and partly by hand, and if the work is not entirely successful, that is due to the defects which were not included in the drainage scheme. It is a safe prediction, I think, that Newark will have no early brood of mosquitoes in 1905, comparable with the invasions of 1903 and 1904."
This prophecy has proved true.
The wealthy summer residents along the north shore of Long Island, keenly alive to the necessity of driving mosquitoes from the region where they spend so much of their time, have attacked the problem in a scientific, as well as an energetic way. The North Shore Improvement Association intrusted the work to Henry Clay Weeks, a sanitary engineer, with whom was associated, as entomologist, Prof. Charles B.Davenport, Professor of Entomology at the University of Chicago and head of the Cold Spring Biological Laboratory; also F. E. Lutz, an instructor in biology at the University of Chicago. Prof. N. S. Shaler, of Harvard University, the most eminent authority in the country on marine marshes, was retained to make a special examination of the salt marshes with a view to recommending the best means of eliminating what were the most prolific breeding grounds of mosquitoes. A detailed examination of the entire territory was made. Practically every breeding place of mosquitoes, including the smaller pools and streams, and even the various artificial receptacles of water, were located and reported on. Mr. Weeks, with his assistant, then examined each body of water in which mosquito larvæ had been found, with a view to devising the best means of preventing the further breeding of mosquitoes in these plague spots. Finally, a report was prepared, together with a map on which was located every natural breeding place.
Important investigations have been made in Connecticut by the Agricultural Experiment Station, under the direction of W. E. Britton and Henry L. Viereck, and the results have been most encouraging. Dr. Howard, in his directions for fighting mosquitoes, acknowledges his indebtedness to the very successfulexperiments carried on at Staten Island. Maryland is aroused to the point of action. Dr. Howard A. Kelley, of Johns Hopkins University, is to coöperate with Thomas B. Symons, the State entomologist, in carrying the war to the shores of Chesapeake Bay. "Home talent," moreover, can accomplish much. To fight intelligently, let it not be forgotten that the battle should be directed against the larvæ. These wrigglers are bred for aquatic life; therefore, it is to all standing water that attention should be directed. Mosquito larvæ will not breed in large ponds, or in open, permanent pools, except at the edges, because the water is ruffled by the wind. Any pool can be rendered free from wrigglers by cleaning up the edges and stocking with fish. Every fountain or artificial water basin ought to be so stocked, if it is only with goldfish. The house owner should not overlook any pond, however small, or a puddle of water, a ditch, or any depression which retains water. A half-filled pail, a watering trough, even a tin receptacle will likely be populated with mosquito larvæ. Water barrels are favorite haunts for wrigglers.
There are those, however, who will obstinately conduct their campaign against the adult mosquito. If energetic, such persons will search the house with a kerosene cup attached to a stick; when this is heldunder resting mosquitoes the insects fall into the cup and are destroyed. Those possessed of less energy daub their faces and hands with camphor, or with the oil of pennyroyal, and bid defiance to the pests. With others it is, Slap! slap!—with irritation mental as well as physical; for the latter, entomologists recommend household ammonia.