450 THE CENT UK Y, 



53- 



A way how to make hollow and 

 cover a Water-fcrue as big and as 

 long as one pleafeth in an eafie and 

 cheap way. 



[An hollowing of a Water-scrue.~] This was probably 

 no more than an ingenious piece of carpentry, to obtain 

 an object which was then most likely of considerable 

 importance. Three of his inventions refer to the 

 Archimedian screw, so that the Marquis seems to have 

 given the subject more than ordinary attention. 



54- 



How to make a Water-fcrue tite, 

 and yet tranfparent, and free from 

 breaking ; but fo clear, that one 

 may palpably fee the water or any 

 heavy thing how and why it is 

 mounted by turning. 



[A transparent Water-scrue.~\ This invention does 

 not appear to be offered as one of any other use than 

 for pleasure and instruction, to &quot; see the water or any 

 heavy thing, how and why it mounteth by turning.&quot; 

 Was it not by such models that he had early informed 

 his own mind ? 



If the transparent covering was not to be glass or 

 horn, the Marquis may have used the material proposed 

 by Sir Hugh Plat in his &quot; Jewel House of Art and 

 Nature,&quot; 1653, in which is given, at page 72, a recipe : 

 &quot; To make parchment clear and transparent to serve 

 for divers purposes. This I commend, (lie says) before 



