president.  We have, by Sir William Armstrong’s system, coupled with his accumulator, the means of transmitting hydraulically the power of a central motor to any place requiring it, and by the means of the principal accumulator, or if need be by that aided by local accumulators, a comparatively small engine is enabled to meet very heavy demands made upon it for a short time.  I think I am right in saying that, at the ordinary pressure which Sir William Armstrong uses in practice, viz., 700 lb. to the square inch, one foot a second of motion along an inch pipe would deliver at the rate to produce one-horse power.  Therefore, a ten-inch pipe, with the water traveling at no greater pace than three feet in a second, would deliver 300 horse-power.  This 300 horse-power would no doubt be somewhat reduced by the loss in the hydraulic engine, which would utilize the water.  But the total energy received would be equivalent to producing 300 horse-power.  Such a transmission would be effected with an exceedingly small loss infliction in transit.  I believe I am right in saying that a 10 inch pipe a mile long would not involve much more than about 14 or 15 lb. differential pressure to propel the water through it at the rate of three feet in a second.  If that be so, then, with 700 lb. to the inch, the loss under such circumstances would be only two per cent. in transmission.  There is no doubt that this transmission of power hydraulically has been of the greatest possible use.  It has enabled work to be done which could not be done before.  Enormous weights are raised with facility wherever required, as by the aid of power hydraulically transmitted, it is perfectly easy for one man to manage the heaviest cranes.  Moreover, as I have said in other places, the system which we owe to Sir William Armstrong has gone far to elevate the human race, and it has done so in this manner.  So long as it is competent for a man to earn a living by mere unintelligent exercise of his muscles, he is very likely to do it.  You may see in the old London docks the crane-heads covered by structures that look like paddle-boxes.  If you go to them, there is, I am glad to say, nothing now to fill them up; but when the British Association first met, these paddle-boxes covered large tread-wheels, in which men trod, so as to raise a weight.  Now, although I know that in fact there is nothing more objectionable in a man turning a wheel by treading inside of it than there is if he turn it round by a winch-handle, yet somehow it strikes one more as being merely the work of an animal, a turnspit, or a squirrel, or, indeed, as the task imposed on the criminal.  But, nevertheless, in this way there were a large number of persons getting their living by the mere exercise of their muscles, but, as might be expected, a very poor living, derived as it was from unintelligent labor.  That work is no longer possible, and is not so, for the powerful reason that it does not pay.  Those persons, therefore, who would now have been thus occupied, are compelled to elevate themselves, and to become competent to earn their living in a manner which is more worthy of an intelligent human being.  It is on these grounds that I say we owe very much the elevation of the working classes, especially of the class below the artisan, to this invention of our distinguished president.