SUCCESSIVE INVENTIONS.

With the wide acceptance in practical use of the Duplex steam pump, may be dated the beginning of the modern inventive period of pumping machinery; this introduction of the Duplex pump was only one of five successive advances which it were well for the student to memorize:

1. The Cornish,2. The Rotative,3. The Direct Acting,4. The Duplex, and5. The Compounded Steam Pump.

The Cornish engines have been alluded to in connection with the Newcomen engine. Probably no large pumping engines in the past have held, and deservedly so, as high repute as have the Cornish engines when used for deep mine pumping. Their construction, with the rude appliances at hand, is not only a marvel but as well a high tribute to the ingenuity of those who designed them and to the skill of the workmen who built them. A rather full illustrated description of this almost unexcelled machine will be found later on in the book.

The next class of large steam pumping-engines which have played an important part in the history of hydraulic engineering may be grouped together as “rotative engines.”What is here meant by the term “rotative” is engines in which there are parts which make complete and continuous rotary motion and in which are used, in some way or another, shafts, cranks and fly-wheels.

These engines vary greatly in their design and in the details of their construction. They are of varying sizes, including some of the largest and most expensive in the world. As a general thing they are employed in supplying towns and cities with water, and in some cases freeing shallow mines of water. The application of the power of the steam used in thesteam cylinders in this class of engines to drive the plungers or pistons in the pumps, varies greatly, both as to the general design upon which they are built, and in the detail of their construction. In some instances it is through the use of long or short beams or bell cranks, sometimes through gearing, and occasionally through the plunger or piston of the pump direct; but in all cases the limit of the stroke of the steam piston, and of the pump plunger, is governed by a crank on a revolving shaft.

Attached to the revolving shaft isa fly-wheelof greater or less diameter and weight, which, in addition to assisting the crank to pass the center at each end of its stroke,is employed to store up at the beginning of each stroke of the steam piston, whatever excess of power or impulse there may be imparted to it, beyond that required to steadily move the water column, and to give out again, toward the latter part of the stroke, when the power of the steam is of itself below that required to move the water column, the power previously stored in it. In this respect the function of a revolving fly-wheel on a rotative engine is the same as is the weighted plunger in the Cornish engine; both being used for the purpose of permitting the steam to be cut off at a portion of its stroke in the steam cylinder, and expanded during the rest of the stroke.

In short, these devices, as employed in both the classes of pumping engines described, were used in order that the best economy in the consumption of steam by means of early cutoff and a high grade of expansion, might be attained.

The succeeding class of pumps to be described, driven by steam aredirect acting steam-pumps.

What is here meant as “direct-acting,” is a steam-driven pump in which there are no revolving parts, such as shafts, cranks and fly-wheels;pumps in which the power of the steam in the steam cylinder is transferred to the piston or plunger in the pump in a direct line, and through the use of a continuous rod or connection. (Fig. 82.)

The introduction of the direct-acting steam-pump marked a point of deviation, and it entered the field almost without a rival, and at a time when economy was overshadowed by its convenience.

In the brief description given of these three most prominent classes of pumping engines, no attempt has been made to describe any of the peculiarities of their general construction, beyond what was necessary to describe their action and the principles upon which they operate.

Fig. 82.

In pumps of this construction there are no weights in the moving parts other than that required to produce sufficient strength in such part for the work they are expected to perform, and, as there is consequently no opportunity to store up power in one part of the stroke, to be given out at another, it is impossible to cut off the steam in the steam cylinder during any part of its stroke. The uniform and steady action of thedirect-acting steam-pump is dependent alone on the use of a steady uniform pressure of steam through the entire stroke of the piston against a steady, uniform resistance of water pressure in the pump; the difference between the power exerted in the steam cylinders over the resistance in the pump governing the rate of speed at which the piston or plunger of the pump will move. The length of the stroke of the steam piston, within the steam cylinders of this class of pumps, is limited and controlled alone by the admission, suppression and release of the steam used in the cylinders.

Note.—Up to the introduction of the direct-acting steam pump, all the other pumping machinery of the world then in use was the outcome of evolution. It had been developed by slow stages, in which one engineer after another aided by the experience of others and of his own, supplemented by his inventive faculties, added here and there slight improvements to which other engineers, with increased experience, were enabled to add still other improvements, so that each new engine constructed under more favorable circumstances, and with increasing expenditures, was supposed to excel all previously built; until at this time we have, as it is fair to suppose, pumping engines which combine all the wisdom of the past, and which leave little or no room for further improvements in their respective classes.

The history of theDirect-Acting Steam Pumpdiffers from all others from the fact that it was the invention of one man, and was in the main perfected during his lifetime. It was so strikingly different from all that had preceded it, that there was nothing in the way of precedent, either in ancient or modern practice, of which the inventor could avail himself by which to aid or guide him to success.

The date of the first patent on these pumps was September 7, 1841. It was issued on a small pump used for supplying feed water to a steam boiler, and consisted of one steam cylinder connected to a force pump, and so arranged that by the use of levers, trips, springs, and other connections between the piston rod and the slide valve, the movement of the piston rod controlled the movements of the slide valve to an extent that not only regulated the length of the stroke of the piston, but reversed its motion. This pump was placed alongside of the steam boiler, and was so connected by means of pipes and levers and floats within the boiler, that when the water fell below the proper level in the boiler, it would start the pump, and stop it when the water rose too high.

Note.—At the head of a list consisting of two names only, who, on the foremost pages of “The American Society of Mechanical Engineers,” are recorded as the “Honorary Members in Perpetuity” of that large society, and standing as well at the head of that long and increasing list of members who have accomplished their work on earth, may be seen the name ofHenry Rossiter Worthington, the inventor and original builder of the “direct-acting steam pump.”

Feeling how incomplete was an invention which did not provide against the intermittent action of the pump, Mr. Worthington devoted much time and study to correct this trouble, and a few years later he brought out an improved pump which, in its simplicity of parts, certainty of action, and cheapness of construction more than rivaled the original invention itself. This pump is now universally known as the “Direct-Acting Duplex Steam Pump.”

In the main, the construction of the steam ends and the water ends of the duplex pump differs but slightly from those of the single-acting pump, but the mechanism which operates the steam valves is different, and the effect on the water column was marvelously different; the principle upon which it operates is this:

Two pumps of similar construction are placed side by side, a lever attached to the piston rod of each pump connects to the slide valve of the opposite steam cylinder; thus the movement of each piston, instead of operating its own slide valve as in the single pump, operates the slide valve of the opposite cylinder. The effect of this arrangement is, that as the piston or plunger of one pump arrives near the end of its stroke, the plunger or piston of the other begins its movement, thus alternately taking up the load of the water column, producing a regular, steady, onward flow of water, without the unusual strains induced by such a column when suddenly arrested or started in motion.

While the “duplex steam pump” overcame one of the greatest objections to the former single pump, there still remained in this class of pumping machinery one other difficulty. It did not use steam expansively.

This not only debarred it from competing with other engines where a large quantity of water was required to be raised, and where the cost of fuel was an item of importance, but as well prevented the pump from taking rank among the hydraulic appliances required in supplying towns and cities.

This objection was one which seemed insurmountable, steam in them could not be used economically. Applied to the propulsion of the plunger or piston of this pump it must be of sufficient quantity, and pressure, to overcome the height of the column of water on the pump, together with its friction through the pump and its connections,at the very beginning of the stroke; and it must be maintained, both as to its volume, and its pressure up to the very last part of the stroke. Any diminution, either of volume or pressure, during any part of the stroke would simply bring the pump to a stop. This apparent inability to cut off the steam in the steam cylinder, and to complete the stroke of the pump by the aid of the steam remaining in the cylinder, and by its expansive force, had debarred this pump from coming into general use for large water works. How this, the only remaining objection to their use for such purposes, was overcome, forms an interesting chapter in the history of the “Direct-Acting Steam Pump.”

It was when this question had assumed a most formidable, importance, that the principle ofusing steam in compound steam engineshad engaged the careful consideration of the most eminent engineers of this and other countries;its adjustment to the Duplex pumps was made, and while it was easily done, owing to their peculiar construction, its application produced a most wonderful result in their working, and their speedy introduction for water works use.

Note.—At this time the man who had invented and built the little steam pump for the canal boat, who had watched its growth and development, supplemented one device after another to help it on through the trial period of its existence, had merged it at last into the dual or duplex stage of its advancement, had added to it the compound feature, had seen it expanding in size and importance until, growing up and out of the day of small things, it had come to take its well-earned place alongside those old and massive machines whose invention and origin was lost amid the musty records of the past—it was, at this time, and of which any man might well have been proud, that his lifelong labors came to an end Dec. 18., 1880, at the Everett House, New York City.

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