HYDRAULICS. 



435 



Mr. Blakey is the only person who ever thought of 

 making use of air as an intermediate body between 

 steam and water : by which means, the steam is always 

 kept from touching the water, and consequently from 

 being condensed by it. And, on this new principle, he 

 has obtained a patent : so that no one (vary the engine 

 how he will) can make use of air between steam and 

 water, without infringing on the patent, and being sub- 

 ject to the penalties of the law. 



This engine may be built for a trifling expence, in 

 comparison of the common fire engine now in use : 

 it will seldom need repairs, and will not consume half so 

 much fuel. And as it has no pumps with pistons, it is 

 clear of all their friction : and the effect is equal to the 

 whole strength or compressive force of the steam ; which 

 the effect of the common fire engine never is, on ac- 

 count of the great friction of the pistons in their pumps. 



AROHIMEDES'S Screw-engine for raising Water. 



A B C D is a wheel, which is turned round, accord- 

 2 P 2 



