Trial of one 

 rudely exe- 

 cuted. 



55 ON DE MOIVUE's doctrines OF CHANCE. 



tlucted, a large supply of mercury is indispensable, for there 

 is scarcely a gas, which is not more or less ^ibsorbable by 

 water. The mercury of the exhausting engine will answer 

 for the mercurial trough in the laboratory, and thus a con- 

 siderable portion of the expense of the machine ought to 

 be deducted. 



In some experiments I made with a rude machine of the 

 kind 1 have described, I found, by anointing the plate and 

 edge of the receiver Mnth hog's lard, that I could raise a 

 column of two feet in height in a receiver open at top, and 

 even could move it along on the surface of the ground plate, 

 without any mercury running out between the plate and re- 

 ceiver. In fitting on the top of the receiver, it may how- 

 ever be proper to press gently with the hand on the receiver, 

 till the atmospheric pressure begins to act on it. 

 Materials. N. B. The whole machine, and its auxiliary apparatus, 



must be made of glass, wood, and iron or steel, on which 

 mercury does not act. 



THO. STEWART TRAILL. 



Liverpool, May 12, 1808. 



Annotation, in Reply to the Doctor's private Letter. 



Though mercury has been used for exhaustion by Dr. 

 Clare, and Sir A. N. Edelcrantz, in air pumps described 

 in our Journal, and by others, I have thought Dr. Traill's 

 contrivance sufficiently original, and different from former 

 apparatus, to be inserted. 



W. N. 



XI. 



J)oubts respecting some of the received Doctrines of Chance. 

 In a Letter from a Correspoyident. 



SIR, 



To Mr. NICHOLSON. 



Durhamy August 9, 1808. 



Some received O^HOULD the following scruples as to the truth of the 

 octruies o elementary doctrines of chance generally admitted appear 



worthy 



