late Professor of Practical Astronomy in Glasgow. 287 



letter from Mr MELVILL to Mr WILSON, dated at Geneva, 21st 

 April 1753, we find, among several other particulars, his curiosi- 

 ty highly excited by the fame of the Philadelphian experiment ; 

 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 WILSON 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 Andrew's, 

 brought his family to Glasgow. About five years afterwards he 

 invented the Hydrostatical Glass-bubbles, for determining the 

 strength of spiritous liquors of all kinds, which long experience, 

 especially among the distillers and merchants in the West Indies, 

 has now shewn to be more accurate and more commodious than 

 the instruments formerly used. From the minutes of a Philo- 

 sophical 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 delivered by Mr WILSON in the winter of 

 1757. At this time he also shewed how a single glass bubble 

 may serve for estimating very small differences of specific gravi- 

 ty 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 sta- 

 tionary at every trial, and then expressing the differences of their 

 specific gravity, by degrees of the thermometer, the value of 

 which can be computed 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 principle 

 of the balance, whose centres of oscillation and motion were verv 







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