my old master, to whom I was apprenticed—­which mode of transmission was then used to a very considerable extent.  The recollection of it, I find, however, has nearly died out, and I am glad to have this opportunity of reviving it.  But in 1881, we have, for the transmission of power, first of all, quick moving ropes, and there is not, so far as I know a better instance of this system than that at Schaffhausen.  Any one who has ever, in recent years, gone a mile or two above the falls at Schaffhausen, must have seen there—­in a house, on the bank of the Rhine, opposite to that on which the town is situated—­large turbines driven by the river, which is slightly dammed up for the purpose.  These work quick-going ropes, carried on pulleys, erected at intervals along the river bank, for the whole length of the town; and power is delivered from them to shafting below the streets, and from it into any house where it is required for manufacturing purposes.  Then we have the compressed air transmission of power, which is very largely used for underground engines, and for the working of rock drills in mines and tunnels.

COMPRESSED AIR LOCOMOTIVES.

We have also compressed air in a portable form, and it is now employed with great success in driving tram-cars.  I had occasion last January to visit Nantes, where, for eighteen months, tram-cars had been driven by compressed air, carried on the cars themselves, coupled with an extremely ingenious arrangement for overcoming the difficulties commonly attendant on the use of compressed air engines.  This consists in the provision of a cylindrical vessel half filled with hot water and half with steam, at a pressure of eighty pounds on the square inch.  The compressed air, on its way from the reservoir to the engine, passes through the water and steam, becoming thereby heated and moistened, and in that way all the danger of forming ice in the cylinders was prevented, and the parts were susceptible of good lubrication.  These cars, which start every ten minutes from each end, make a journey of 33/4 miles, and have proved to be a commercial and an engineering success.  I believe, moreover, that they are capable of very considerable improvement.

HYDRAULIC TRANSMISSION OF POWER.

Then there is, although not much used, the transmitting of power by means of long steam pipes.  There is also the transmission hydraulically.  This may be carried out in an intermittent manner, so as to replace the reciprocating flat rods of old days; that is to say, if two pipes containing water are laid down, and if the pressure in those pipes at the one end be alternated, there will be produced an alternating and a reciprocative effect at the other, to give motion to pumps or other machinery.  There is also that thoroughly well known mode of transmission, hydraulically, for which the engineering world owes so much to our