168 Biographical Account of [March, 



nate consequence of this vice is to deprive its victim of the 

 power of reflection. The dissertation of course could not be 

 expected to produce any other effect, except demonstrating the 

 goodness of heart and the patriotism of the author. 



Similar motives seem to have led him to examine the nature 

 of sea water, the method of rendering it fresh and drinkable, and 

 of preserving corn, meat, and all sorts of provisions fresh during 

 long sea voyages. These experiments, together with many 

 useful instructions to navigators, constituted a work which he 

 pubUshed in 1739, and which he dedicated to the Lords of the 

 Admiralty. For this work the Copleyan metal was voted to him 

 by the council of the Royal Society. The reputation which he 

 had acquired by his work on the urinary calculus, and the utihty 

 of that work, induced him in 1740 to examine the nature of Mrs. 

 Stephens's famous cure for the stone, which had just been pur- 

 chased by Parhament. He endeavours to point out the 

 importance and efficacy of this remedy, which was then at the 

 height of its reputation. But many years have elapsed since 

 that ephemeral reputation has vanished, and now it is admitted 

 by all that no solvent for the stone can be applied without the 

 risk of fully as great an injury to the constitution as that which 

 it proposes to cure. 



Three years after, he published a description of the ventilator 

 — an instrument by means of which we may at pleasure renew 

 the air in all places where we have occasion to do so. It seems 

 unnecessary to give a description of this simple and ingenious 

 machine, as it is sufficiently known, and as a method of renewing 

 the air in the cabins of ships is very generally used in this coun- 

 try, which may be considered as little else than a simplification 

 of Hales's ventilator. This description of the ventilator was the 

 last separate work published by Dr. Hales. He was then 60 

 years of age, and did not choose after that period of hfe to 

 venture upon long publications. But he inserted a great many 

 interesting papers in the Transactions of the Royal Society. . Of 

 these, it seems requisite only to notice the most important. 



Dr. Berkeley had brought tar water into fashion as a medicine, 

 and its virtues were highly extolled all over Europe. Dr. Hales 

 w-as too much of a philosopher to be led away by the enthusiastic 

 encomiums passed upon any medicine whatever. He examined 

 tar water, and pointed out the diseases in which it might be 

 used with advantage, or at least innocently, and the cases in 

 which it would be improper to employ it. Tar water has long 

 ago lost its reputation, and is no longer employed in medicine ; 

 but Dr. Hales's opinions respecting it ought not to be forgotten, 

 as they show us how far he rose above the prejudices of his age, 

 and the care he took to investigate opinions before he admitted 

 them. In the same year (1745) he pointed out a method of 

 stopping the progress of combustion by covering with a layer of 

 moist earth those buildings through which it was hkely the 



