Edmlurgk Jnstttuie. 153 



gallon of that liquid ; and, in the same way, the weight of 

 any larger quantity may be found. On the other hand, 

 the weight and specific gravity being given, it is equally 

 easy to find the number oF gallons. Such a method would 

 evidently be less convenieiu than measurement, when ap- 

 plied to small quantities of liquor; but, on a large scale, it 

 would certainly be found greatly preferable. A cask hold- 

 ing 180 gallons, for instance, when filled whh a .5-gallon 

 measure, according to the present practice of spiril-deaiers, 

 requires 36 distinct manipulations, each of which ought 

 to be conducted with considerable care and attention. But 

 such a cask might be filled with equal accuracy, and less 

 labour, and in a much shorter time, by weighing the cask, 

 first when empty, and afterwards when full : ihe difference 

 of these weights would of course be the weight of the spi- 

 rits, from which the bulk or measured quantity might be 

 obtained, as already stated. Such is the method proposed. 

 It has been already put in practice by a few individuals, and 

 Would probably have been generally adopted, had it not in- 

 volved calculations too laborious for practical men, — a dis- 

 advantage which the correct and ampie tables Mrs. Levi 

 has now in the press will completely obviate. 



It has ;>lready been staled, thai this method is niore ex- 

 peditious than common measurement, and it may be added 

 that it is more ceconomicLi: ; as, by substituting one opera- 

 tion for a great number, it avoids the waste occasioned by 

 the frequent mechanical agitation of the spirits, and the 

 loss that constantly altcufls a series of small operations. 

 Superior accuracy, however, will be found to be its greatest 

 recommendation. This it owes to several circumstances : 

 1. Because measures are seldom made with the same ac- 

 curacy as weights ; 2. Because thev have their capacities 

 changed by variations of temperature, or by accidents, and 

 fire niuch more acted upon by air and moisture ; and lastly. 

 Because they do not show excess or deficiency in the quan- 

 tity of the substance measured, with so much precision. 



2. Account of an improved crane, invented by Mr, Kerr, 

 mathematical instrument maker. 



The base of this machine rests upon cones, by which the 

 horizontal motion is effected ; and the arm is lengthened 

 or shortened by a peculiar contrivance, of which it would 

 J)e dilHcult to convey an adequate idea without a diagram. 

 This improvement obviates, the difficulties which have long 

 been experienced in the use of cranes. With its assistance, 

 a weight may be l.iid down, with the greatest accuracy, on 

 any point wltldn the area of the circle described by the 



extremity 



