5.rc- SPEEDY ELEVATOR. 



whole of thefe.* They ha^'e fimilar grooves, emhrazures, 

 pulleys, and joining ribs. Their faces are parallel redlan- 

 glcs. The backs of their bodies have tongues along the 

 middles that fit the grooves of A A. Thefe are vertical 

 redlangular ridges, and parts of the very pieces, fornned 

 by cutting down both fides to a proper level. Thefe lower 

 lurfaces, being even and fmooth, will thus move clofe 

 along the correfponding plain parts of AA while the 

 tongues glide in contad: with the fides of the grooves. 



The cords a a are well paired in length and texture. 

 They ply over the pulleys of A A in the faid hollows be- 

 hind the grooves ; having their ends fixed under the feet 

 of B B, and on the boxes of the windlafs. This is well 

 fecured in the bale, clofe to and right beneath the pillars. 



The cords b b are faftened by one end on the heads of 

 A A. They pafs over the pulleys of B B, and reach as 

 far below them as (7 a reach below the pulleys of A A, which 

 is the diftance of thefe pulleys from the bafe. Their other 

 ends are tacked a little above the bottoms of the piers C C. 



Thefe piers are with their apparatus framed like B B ; 

 liave lefs bulk and fliorter heads. Their pulleys clear the 

 tops of B B when the machine is down. 



The cords c c have the fame length with b b^ below the 

 pulleys of GC ; plying over thefe ; faftened on the heads 

 of B B and fomewhat above the bottom of the pier D. 



This is a fingle piece. It has two backs to fit the grooves 

 of C C, formed like the backs of the other pieces. 



A frame is accurately fixed and poifed on the top of D. 

 In this the load L is placed, fo that its centre of gravity 

 is exadlly or very nearly over the centre of the frame. 



When the power begins to wind the cords a a, thefe 

 raife the piers B B. As they rife, their pulleys recede 

 from the tops of A A, and by ftretching the cords b b lift 

 the piers C C. Thefe recede at the fame time from the tops 



of 



" I call the part about the emb:azure luxl, tli.U above head, and that he- 

 Io%N- body. 



