Depression in Capillary Tubes. 421 



In the same manner, we obtain for the cylinder, which was 

 weighed in air under the same circumstances, and in water at 

 60*5°, the difference being 19006-83 grains, the correction 

 T5T-I4-T'T for the effect of buoyancy, amounting to 19"43 grains; 

 and for the difference of temperature of the water and brass con- 

 jointly, the densities being -QDODSS and "999810, the correction 

 •000 145 --000047= -000095, or 1-80 grains, leaving + 17'63 

 grains for the whole correction of the weight, as reduced to a 

 vacuum at 62°, and making it 19024-46, which divided by 

 75-2398, the content of the cylinder, affords us 252*851 for the 

 cubic inch in a vacuum at 62°. 



The sphere was weighed in air at 67°, the barometer standing 

 at 2974 ; the correction for buoyancy is here |-;a.s^9,_|_.j or 

 for 2S673'51 grains, 29-72; while the temperature of 66° re- 

 quires, for the difference between the expansion of brass and wa- 

 ter, the addition of -00042 --0001 26, or -000294 of the whole, 

 that is +8-43 grains, making the whole correction 38-15, and 

 the weight in a vacuum 2871 1-66; which, divided by 1 13-5264, 

 gives us 252-907, for the cubic inch in a vacuum. 



The mean of these three measures is 252-888, giving for the 

 three errors +-019, —-037, and +-019; and this mean, re- 

 duced to the Parliamentary Standard, makes 252-722 grains, for 

 the cubic inch of distilled water at 62°, weighed in a vacuum, or 

 252-456 in air, under the common circumstances of the atmo- 

 sphere, when weights of brass are employed. In a vacuum ak 

 the maximum of density, that is at 39®, the weight of a true cubic 

 inch will be 253 grains, and of a cubic decimetre 15440 *. The 

 proposed Imperial gallon, of ten pounds, or 70000 grains, of 

 water, will contain very nearly 27 7 "3 cubic inches, under com- 

 mon circumstances. 



LXXVI. Observations on the Letter in last Number respecting 

 the Caladation of the Depression of Mercury in Capillary 

 Tubes f. By James Ivory, M.A. F.R.S. 



Sir, — A FIND in your last publication, another letter on the 

 subject of the depression of mercury in capillary tubes, full of wit, 

 and banter, and heavy charges of error, but containing nothing 

 new in point of argument. 



In the Conn, des Terns 1812, Laplace published an article on 

 the Depression in Barometer-tubes, accompanied with a Table. 

 The illustrious foreigner notices a similar Table, computed by 



[* It appears, however, from an official Report, obligingly communicated 

 to us by Dr. Kelly, tbat the actual standard chilograinmc lius been found to 

 contain only 15433 English grains.] 



t Sec Phil. Mag. for last mouth, p. 3/6. 



nicutib 



