CATALOGUE. PHILOSOPHY AN'D ARTS, PUACTICAL MECHANICS. l6l 



Hutton's recreations. II. 152. 

 Fletcher onShuckburgh's experiments. Nich. 

 8. IV. 55. 



A gramme, the standard of the new French weights, is 

 the weight of a cubic centimetre of pure water, at its maxi- 

 mum of density,n.08l0280 cubic inches, English. The 

 cubic dfcimetre vias found to weigh in a vacuum 1 S8-37.I5 

 grains of the marc of Charlemagne, which differed a little 

 from Tillet's. The chiliogramme of platina wa^ adapted for 

 a vacuum, that of brass for the air. The cubic foot of water 

 weighed 70 pounds 223 grains, at its maximum ; 70 pounds 

 130 grains at the freezing point. M. Inst. H. "01. Hence 

 a pound is 489.5058 grammes, a gramme I8.82;i5 grains 

 French. According to Coquebert Montbret, a pound is 

 only 48y.l47 grammes. B. Soc. Phil. n. 74. 



It may be inferred from Sir George Shuckburgh'j experi- 

 ments, that the diameter of a sphere being 6.0074 5 inches, 

 it loses 28715.85 grains of Troughton in water, reduced to 

 Jy°, or the maximum of density of water, the air at 39°, 

 the barometer at 30., the standard brass scale employed at 

 62^. Hence, under these circumstances, tire weight of a 

 cubic inch of water, weighed against brass in air, is 252.8033 

 parliamentary grains: in vacuo 253.094; of a cubic foot 

 in air 43684.41 grains::z998.5 oz. av.i::62.4063 pounds 

 av. ; in vacuo 43735.6 grains— 999. C? ounces:z62.48 

 pounds. 



If we reduce these measures to more usual temperatures, 

 the barometer being still at 30, the weight of a cubic inch 

 at 52° will be found 252.08 grains ; of a cubic foot 998 

 ounces ; at 60°, the temperature employed by Gilpin, 

 252.56 grains, and 997.0 ounces; at 62°, the standard 

 temperature of English measures, 252.52 grains, and 997.4 

 ounces. At this temperature, four cubic inches make 1010 

 grains, and 12 gallons exactly 100 pounds avoirdupois. 



Mr. Fletcher finds some other experiments of Sir G. 

 Shuckburgh more accurate than the author supposed them, 

 and therefore takes a mean of the whole. After all cor- 

 rections, the barometer standing at 29.5, the temperature 

 60°, th« cubic inch of water appears to weigh in air 

 252.519 grains from the experiments on the cube, 252.432 

 from the cylinder, and 252.568 from the sphere ; the mean 

 being 252.500 ; in a vacuum 252.806. _If the barometer 

 be at 30, the weight from the sphere will be 252.563, nearly, 

 as already stated, and the mean 252.501 ; we may there- 

 fore call it accurately 252.50; in a vacuum 252.77; for 

 we must not add .3, which is the whole weight of a cubic 

 inch of air, but only the difference between the weight of 

 air and of brass. The French experiments, reduced to the 

 same circumsunces, give 252.56, and 352.83, agreeing 

 VOL. II. 



with the sphere ; taking the gramme— 1 5.44 403 gr. If we 

 prefer Mr. Fletcher's mean, we must make the gramme— 

 15.440 grains. 



Professor Robison found a cubic foot at 55° weigh 998.74 

 ounces. Enc. Br. Art. Specific gravity. Hence, a cubic inch 

 is equal to 252j at 50° ; but his weights were not so well 

 authenticated as Sir G. Shuckburgh's. Atkins on Specifie 

 Gravity. 



Jacquin found a cylinder, 1 inch in diameter, 2 inches 

 long, lose,'in distilled water, 393.6 grains apothecaries weight 

 of V'ienna, the thermometer being at 43°, the baroraetcf 

 2Si inches of Vienna ; it was weighed in air. 



English Weights. 



The avoirdupois ounce is supposed by Barlow to be the 

 thousandth part of a cubic foot of water. The avoirdupois 

 pound has been found to weigh 7001.5 or 7000.5 grains troy. 

 Ph.tr. 1743. 



A pennj'wcight, troy is G4 gr. 



An ouncCj or 20 pennyweights, 480 

 A pound, or 12 ounces, 5700 



A drachm, avoirdupois, is 27.35 gr. troy. 



An ounce, or \6 drachms, 437.5 



A pound, or iG oz. about 7000. 



A stone is 14 pounds; a quarter 28 pounds; 

 a hundred weight 112 pounds; a ton 20 

 hundred weight, or 2240 pounds. 



A scruple, 9j, apoth. weight, is 20 gr. troy. 



A drachm, 5j, or 9iij, 60 



An ounce, ^, or S^'U' '^SO 



A pound, ftj, or ^xij. 5760 



Ten ounces troy are nearly Cijual to 1 1 avoirdu] 

 17 pounds troy to 14 avoirdupois. 





Scotch Weights. 



An ounce is 476 grains troy. 

 A pound trone is 20 ounces ; a stone 16 

 pounds. 



Old French Weights. 

 A grain is .8203 gr. Eng. 



A denier, 24 gr. French, 19.69 

 A gros, 3 deniers, 59.06 



An ouuce^ 8 gros, 478.5, ^i oz. troy. 



A marc, 8 ounces, ^780. 



Y 



