8 Biographical Account of Dr Wilson^ 



21st April 1753, we find among several other particulars, his 

 curiosity highly excited by the fame of the Philadelphian ex- 

 periment ; and a great ardour expressed for prosecuting such 

 researches by the advantage of their combined kites. But, in 

 the December following, this beloved companion of Mr Wil- 

 son was removed by death, — to the vast loss of science, and to 

 the unspeakable regret of all who knew him. 



In the year 1752, Mr Wilson, who had married Jean 

 Sharp, daughter of William Sharp, a reputable merchant at 

 St Andrews, brought his family to Glasgow. About five 

 years afterwards, he invented the hydrostatical glass-bubbles, 

 for determining the strength of spirituous liquors of all kinds, 

 which long experience, especially among the distillers and mer- 

 chants in the West Indies, has now shown to be more accurate 

 and more commodious than the instruments formerly used. 

 From the minutes of a Philosophical and Literary Society, 

 composed of the professors and some of their friends, whose 

 meetings were held weekly within the college, it appears that 

 these hydrostatical bubbles made the subject of a discourse de- 

 livered by Mr Wilson in the winter of 1757. At this time he 

 also showed how a single glass-bubble may serve for estimating 

 very small differences of specific gravity of fluids of the same 

 kind, such as water taken from different springs, or the like. 

 This he did by varying the temperature of such fluids, till the 

 same bubble, when immersed, became stationary at every trial, 

 and then expressing the differences of their specific gravity, by 

 degrees of the thermometer, the value of which can be com- 

 puted and stated in the usual manner. 



In the year 1758 he read another discourse to the same so- 

 ciety upon the motion of pendulums. On this occasion he ex- 

 hibited a spring-clock of a small compass, which beat seconds 

 by means of a new pendulum he had contrived, upon the prin- 

 ciple of the balance, whose centres of oscillation and motion 

 were very near to one another. At one of the trials it per- 

 formed so well as not to vary more than a second in about forty 

 hours, when compared with a very exact astronomical clock 

 near to which it was placed. It was some view of rendering 

 much more simple and cheap the machinery of ordinary move- 



