[ 3«4 ] 



A. (fig. 4 ) A hollow axle-tree, made in feparate pieces, hooped 

 together in the form of a double truncated cone, on the midlde 

 of which is faftened a wheel of wood (b. fig. 4.) with eight not- 

 ches cut out (a. fig. 4.) to receive eight ribs (t. tr. t. t. V. V- t. P. 

 fig. I. and 2.) Thefe ribs turning on a ftrong iron ring, fhut up 

 like the ribs of an umbrella, and are raifed and adjuftcd by cords 

 pafling through eight holes in the flanches or fhoulders (F. fig. i. 4.) 

 Thefe flanches, and thofe at (f. fig. 2. and 4.) ferve to keep the 

 machine in its place upon the (lands which fupport it (fig. 2.) 

 the cords are ftrained and faftened like the cords of a tent 

 (c. c. &c. fig. 2.) 



Where permanent buildings are not required, fupports for 

 thefe machines may be conftruded in the following manner: 

 Two ftands, each of them made of two pieces of wood fimply 

 bolted together as (fig. 3.) muft be ereded, and held fteady by 

 means of cords (c. c.) faftened to common tent pegs as in 

 (fig. 2. P. P. P.) When the machines are large, fmall piles fhould 

 be ufed inftead of pegs, and running tackle (t.) ftiould be ufed 

 both for the cords of the pointers and the ftands. A number of 

 minute circumftances ftiould be attended to in the conftrudion 

 and ufe of thefe machines ; but I do not think it proper to de- 

 tail them to this Academy ; they ftiould appear in a different 



place (a). 



^ '^ Besides 



fnj Formerly In France every engineer, who condufted any public work, was 

 obliged to lodge in a public office exafl drawings wi^ minute defcriptions of every 

 part of and procefs of his operations. Numbcrlefs fmall improvements in work- 



manfliip 



