381 
He had then this parallelogram raised vertically * hemadettie 
truncated end of the screw at E. to-rest upon the lower cross 
"board, and passed through the middle of the upper board a 
round iron gridiron at F. from three to four inches in dia¬ 
meter, and eight in length, which was driven into the end of 
the screw, to serve it as a centre of motion, and to keep it in 
its place. The wheel and spokes having been removed, there 
remained four mortoises; as the spars obstructed the working 
of the screw, he had four more mortoises added, G. in the 
Space between the former ones, that it might the more-comma,, 
diously be worked with a lever. 
By means of this supplemental part, at once ingenious and 
simple, he was able, without losing any time, to make that 
screw as useful as a new one; it then bore'against the top; 
instead of that before, it bore against the bottom. Ti>e dou¬ 
ble screw, repaired in this manner, succeeded perfectly well 
during the seas and might have lasted for many years 
jonger, if it had no been taken down to make room for a sin¬ 
gle screw of iron in its place- 
"With a view to facilitate the carriage of a large quantity of 
hay within a small compass, press has been invented in Eng¬ 
land, which is now actually used to condense the trusses, and 
which makes them as hard as beards. This surprising effect is 
the result of an hydrostatic pre“?s, for which Mr. Bramah, the 
inventor, obtained a patent in 1796. I mention that machine, 
as it might be made serviceable in aider-making ; it is possible, 
that after the patent is expired, it will be used for that pur-, 
jposej at present, it is very dear, 
' CHAPTER 
