420 Appendix to Third Report on Weights and Measures. 



to that immense code of meteorology collected from all parts of 

 Europe, and published in five quarto volumes by the Society of 

 Meteorology formed and directed by the late Elector Palatine. 

 I liave the honour to remain, sir, &c. 



T. FORSTER. 



To the Editor of the Phil. Mag. 



LXXV. Appendix to the Third Report of the Commissioners 

 appointed by His Majesty to consider the Subject of Weights 

 and Measures. 



A HE Commissioners having been furnished, by the kindness of 

 the Hon. Charles C. C. Jenkinson, with the apparatus employed 

 by the late Sir George Shuckburgh Evelyn, in the determination 

 of the magnitude of the standard weights, and there being some 

 doubt of the perfect accuracy of his method of measuring the 

 capacity of the bodies employed, it was judged necessary to re- 

 peat that measurement with greater precautions ; and the results 

 of Captain Kater's experiments have afforded some slight cor- 

 rections of the capacities in question. 



The sides of Sir George Shuckburgh's cube were found by 

 Captain Kater equal to 4-9891 1, 4-98934, and 4-9S935 inches; 

 the diameter of the cylinder 3-99713, and its length 5-99600 

 inches ; and the diameter of the sphere 6-00759 inches. Hence 

 the content of the cube appears to be 124-1969 inches; that of 

 the cylinder 75-2398; and that of the sphere 113-5264 inches 

 of Bird's Parliamentary Standard of 1760, recommended in the 

 last Report of the Commissioners, or of the Standard made by 

 Trouchton for Sir George Shuckburgh. 



The difference of the weight of the cube in air at 62°, with 

 the barometer at 29-0, and in water at 60-2°, was 31381-79 

 grains ; and, adding to this the weight of an equal bulk of the 

 air at 62", which is -g^-l-^- of that of the water, or 36-26 grains, 

 and subtracting from it -.-^ of this, or 4-26 grains, the buoyancy 

 of the brass weights, we obtain 31413-79 grains for the weight 

 of the culie of water in a vacuum at ()0-2°. Now this cube is less 

 than the supposed measure at the standard temperature of 62", 

 in the ratio of 1 to 1-0000567, on account of the contraction of 

 the brass ; and the water is denser than at the standard tempe- 

 rature, according to Mr. Gilpin's experiments, in the ratio of 

 •99998 to -99981, or of 1-00017 to 1, the whole correction, for 

 the difference of I'S", being '0001 133, or 3*55 grains, making 

 51410-24 for the weight of the cube of water in a vacuum at 

 62"; which, divided by 124-1969, gives 252-907 for the weight 

 of a cubic inch in Sir George Shuckburgh's grains. 



In 



