yLvY^diiionNetvMkrcmeters. 125 
the second will also be so. This scale could not, however, be a 
scale of equal parts, but one which could easily be laid down. 
I made a rough model of this instrument at the time, but 
have never completed it, having been since engaged in con- 
cerns where such instruments were unnecessary. I descri- 
bed it, however, to several of my friends -at the time, and, 
among others, to the late Mr Ramsden ; but whether it has 
been thought of by any one else, or the. problem published, I 
am ignorant. 
Art. XXII . — Accoimt of Mr Morton's Patent Slip^for hauh 
mg Vessels out of the water to he repaired^ Drawn up 
from information communicated by the Inventor. 
There are few of the practical inventions of the present day 
that are entitled to a higher rank, in point of real utility, than 
the slip recently invented by Mr Thomas Morton of Leith, for 
hauling vessels out of the water in order to be repaired. Some 
years ago Mr Morton conceived the idea of superseding the ne- 
cessity of dry-docks by the use of a simple apparatus. He ac- 
cordingly erected one in his own dock-yard at Leith ; and 
after experiencing its benefits, and bringing it to perfection by 
successive improvements, he secured, by a patent, his exclusive 
riglit to the invention. 
This apparatus, which he calls a Slip^ is represented in section 
in Plate I. Fig. 6. where A, B, C are the sections of three 
railways constituting a plane, inclined at nearly the same angle 
as the slips generally used for building ships. This railway is 
placed on a sloping beach, and extends from above the reach of 
the tide down to low water-mark. A carriage or frame of 
wood, seen in section at D, E, F, G, H, runs along the iron rail- 
way upon rollers or truck-wheels., having flanges to guide them. 
Blocks are laid upon the middle or keel-beam E, of the car- 
riage, to such a height, that the keel of the vessel may clear the 
ends of the cross-pieces D, F ; and each block embraces four 
trucks, two on each side of the beain. The blocks seen at M 
and N, which slide upon the cross-pieces, are made up to cor- 
respond to the rising of the vessel's bottom. They run cut to 
