2-11 Method of ohviatbig 



power to the rams, and decrease of labour to the artificer?^; 

 besides which, the blows are given with much more exact- 

 ness. The same blocks were again laid in aiiother dock, in 

 which a two-decked ship of the line was docked. On exa- 

 mination thev were found to be very severely pressed, but 

 were removed with great ease. They were again placed ia 

 another dock in which a three-decked ship of the line was 

 docked. Tiiis ship having in her foremast and bowsprit, 

 the blocks were put quite forward, that being the part which 

 presses them witli the greatest force. As soon as the water 

 v.-as out of the dock, it was observed that the horizontal 

 v/edges of nine and seven degrees had receded some feet 

 from their original situations. This alTorded Mr. Scppings 

 a satisfactory proof, which experience has since demon- 

 strated (though many persons before would not admit of, 

 and others could not understand, the principle), that the 

 facility of removing the blocks or wedges, was proportionate 

 to the quantity of pressure upon them. The block of five 

 degrees kept its place, but was immediately cleared, bv ap- 

 plying the power of the battering-rams to the sides of the 

 outer ends of the horizontal wedges. The above experi- 

 ments being communicated to the Navy Board, Mr. Sep- 

 pings was directed to attend them, and explain the prin- 

 ciple of his invention; which explanaiion, further corro- 

 borated by the testimonials of his then superior officers, 

 was so satisfactory, that a dock was ordered to be fitted at 

 Plymouth under liis immediate directions. The horizontal 

 wedges in this, and in the other docks, that were afterwards 

 fitted by him, are of cast iron, with an angle of about five 

 degrees and a half, which, from repeated trials, are found 

 equal to any pressure, having in no instance receded, and, 

 when required, were easily removed. The vertical wedge 

 is of wood, iiued with a plate of wrought iron, half an inch 

 thick. On the bottom of the dock, in the wake of eacii 

 block, is a plate of iron of three quarters of an inch thick, 

 so that iron at all times acts in contact with iron. 



The placing the sustaining shores, the form and sizes of 

 the wedges, and battering-rams, &c. ; also the process of 

 taking away, and again replacing, the' wedges of which the 

 block is composed, are also exemplified by a model. 



The dock being prepared at Plymouth, in August ISOl 

 the Canopus, a Urge French SO-trun ship, was taken in, 

 and rested upon the blocks ; and the complete success of 

 the experiment was such, that other docks were ordered to 

 be fitted at Shecrness and Portsmouth dock-yards, under 

 Mr. Sepplngs's directions. At the former place a frigate, 



and 



