ON THE STANDARD OF WEIGHT AND MEASURE* $£ 



VI. 



Obfervations on Sir George Shuckburgh Evelyn's Paper * in the 

 Philofophical Tranfaclions for 1798, on the Standard of Weight 

 and Meafure, By J. Fletcher, Efa % Communicated by 

 the Author, 



I. HAVING about two years ago had occafion, in the courfe Occafion of tint 

 of fome inveftigations in which I was then engaged, to afcer- y * 

 tain with as much precifion as waspollible the relation between 

 the known meafures of diftilled water and their refpective 

 weights at different temperatures ; Sir George Shuckburgh 

 Evelyn's Paper on this fubject was of courfe confidered as the 

 beft authority with regard to what had been previoufly done in 

 this refpect. I found however, on looking into it, fome er- Numerical er- 

 rors in the calculations, which render the deductions from £° rs in S"* G. S. 



' Evelyn s paper, 



them incorrect, at the fame time that they more ftrongly con- 

 firm and eftablifh the accuracy of the experiments on which 

 they are founded. I have no doubt, therefore, that the gen* 

 tleman to whom we are fo highly indebted for the communi- 

 cation of the facts which he dates in this important effay, will 

 feel rather obliged than otherwife by their correction. The Apparent differ- 

 circumftance which firft induced me to repeat the calculations, encc in refult,# 

 was the difference which there appears to be in the refults of 

 the experiments with the cube and fphere, and that with the 

 cylinder, and which Sir George afcribes, in § 24 and 31 of 

 his Paper, to either a difference in the denfity of the water at 

 different depths, or to the compreflibility of the cylinder em- 

 ployed. I was however as much pleafed as furprized to find, Miftake In the 

 that it altogether arifes from a miftake in the multiplication of ^f c XdeV. 0t 

 the four numbers whofe product is equal to its folid content, 

 viz. 3.99745 x 3.99785 X 5.99502 x .78539816, which he 

 makes 74.94823 cubic inches, inftead of 75.247149, which is 

 the real product. This naturally fuggefted the propriety of 

 examining the whole, and the refults of this examination are 

 what I (hail now lay before the public through the medium of 

 the Philofophical Journal. The power of correctly appreci- 

 ating and comparing fpace and quantity are fo eflential to 



* Copied in the Quarto Series of this Journal, III. 197. 



D 2 *ver^ 



