Manchester Memoirs, Vol. lix. (191 5), No. 11. 11 



states and towns — a feat alone of sufficient importance 

 to have perpetuated his memory. Every day we make 

 use of the methods of computation which he introduced. 

 Engineers and physicists apply every instant the principle 

 of the decomposition of forces and the principles of 

 hydrostatics which he added to the work of Archimedes. 



The system of defence by opening the sluice gates 

 was applied and is still applied in the present war at 

 Termonde, at Antwerp and in the valley of the Yser. 

 If Holland has been for centuries a land renowned for 

 liberty, where so many of the oppressed have found 

 refuge and where so many thinkers have been able freely 

 to express their opinions, it is in part at least due to the 

 fact that Stevin the Fleming made of it an impregnable 

 citadel and a shelter from tyranny. Among the heroes 

 whose memory history has preserved, there are very few 

 of a purer renown or a more beneficial achievement. 



Simon Stevin has often been compared with Archi- 

 medes, and in fact the careers of these two men offer 

 numerous analogies. Let us combine the two in imagi- 

 nation, and, to form some estimate of their greatness, try- 

 to think of all that we should to-day lack if they had 

 never lived. 



Among the inventions of modern times, there is per- 

 haps none the influence of which on history has been so 

 great as that of the steam engine. This invention was 

 not made at one stroke ; in other words, the steam engine 

 has, during its long evolution, passed through a series of 

 successive stages, which correspond to as many improve- 

 ments. In studying this evolution we are led to admire 

 not merely the cleverness of a certain number of in- 

 genious inventions, but also the creative power of purely 

 scientific principles. We will endeavour to demonstrate 

 this in the following short survey. 



