Such a saving of time in the performance of similar work -- by steam versus manual labour -- had never before been witnessed. The energetic action of the steam hammer, sitting on the shoulders of the pile high up aloft, and following it suddenly down, the rapidly hammered blows keeping time with the flashing out of "the waste steam at the end of each stroke, was indeed a remarkable sight. When my pile was driven, the hammer-block and guide case were speedily re-hoisted by the small engine that did all the labouring and locomotive work of the machine; the steam hammer portion of which was then lowered on to the shoulders of the next pile in succession. Again it set to work. At this the spectators crowding about in boats, pronounced their approval in the usual British style of "three cheers!" My new pile-driver was thus acknowledged as another triumphant proof of the power of steam.

The whole of the piles for this great work were speedily driven in. The wall was constructed, and the docks were completed in an unusually short time. The success of my pile-driver was followed by numerous orders. It was used for driving the immense piles required for the High Level Bridge at Newcastle, the great Border Bridge at Berwick-upon-tweed, the Docks at Tynemouth, the Docks at Birkenhead, the Docks at Grimsby, the new Westminster Bridge, the great bridge at Kief in Russia, the bridge at Petersburg, the forts at Cronstadt, the Embarrage of the Nile, at Yokohama in Japan, and at other places. It enabled a solid foundation to be laid for the enormous superstructures erected over them, and thus contributed to the permanence of many important undertakings.

The mechanical principles on which the efficiency of the steam pile-driver chiefly depends are as simple as I believe they are entirely novel and original. The shoulder of the pile acts as the sole supporter of the ponderous mass of the hammer-block, cylinder, and guide-box. This heavy weight acts as a predisposing agency to force the pile down, while the momentum given by the repeated fall of the hammer, at eighty blows the minute, brings the constant dead weight into full action. I am not aware of any other machine in which such a combination of mechanical forces is employed.

Another very effective detail consisted in employing the waste steam in the upper part of the cylinder for the purpose of acting as a buffer to resist any undue length of the upward stroke of the piston. But for this the cylinder covers might have been knocked off. The elastic buffer of waste steam also acted as a help to the downward blow of the hammer-block. The simplicity and effectiveness of these arrangements form -- if I may be allowed to say so -- a happy illustration of my "Definition of Engineering," the application of common sense in the use of materials.

The folding-up steam pipe with which the steam was conveyed from the boiler to the cylinder at all heights, and the way in which the folding joints accommodated themselves to the varying height of the cylinder, was another of my happy thoughts. In fact, this invention, like most others, was the result of a succession of happy thoughts. The machine in its entirety was the result of a number of common-sense contrivances, such as I generally delight in. At all events, this most effective and novel machine was a special favourite with me.

I may mention, before concluding this branch of my subject, that pile-driving had before been conducted on what I might term the artillery or cannon-ball principle. A small mass of iron was drawn slowly up, and suddenly let down on the head of the pile at a high velocity. This was destructive, not impulsive action. Sometimes the pile was shivered into splinters, without driving it into the soil; in many cases the head of the pile was shattered into matches, and this in spite of a hoop of iron about it to keep the layers of wood together. Yet the whole was soon beat into a sort of brush. Indeed, a great portion of the men's time was consumed in "reheading" the piles. On the contrary, I employed great mass and moderate velocity. The fall of the steam hammer-block was only three or four feet, but it went on at eighty blows the minute, and the soil into which the pile was driven never had time to grip or thrust it up -- an impediment well known to ordinary pile-drivers. At the end of the driving by my steam hammer, the top of the pile was always found neat and smooth, indeed more so than when the driving began.

I may again revert to my interview with the Lords of the Admiralty on the occasion of my first meeting them at Devonport. I was residing at the hotel where they usually took up their quarters while making