VOL. Xtr,] PHILOSOPHICAL TRANSACTIONS. 543 



in his Dissertationes Physico Mathematicae, Lend. 1732, 8vo. This gentleman 

 has also, in N° 369 of the same Transactions, obliged us with some very judi- 

 cious and useful remarks, relating to the caution to be used in examining the 

 specific gravity of solids, by weighing them in water; for want of attending to 

 which, several sorts of bodies, such as human calculi, the substance of all woodsj 

 &c. have appeared, from their pores and small cavities filled up with air, to be 

 considerably lighter than they really are. 



John Woodward, m. d. and professor of physic in Gresham College, had, as 

 he acquaints us in several places of his works, made a great number of experi- 

 ments on the specific weights of mineral and other fossil bodies, but which 

 being probably contained in those of his papers which he ordered to be suppressed, 

 are thus lost to the world, to which they would doubtless have been very accepta- 

 ble. All that Dr. D. has been able to pick up, are a very few mentioned in the 

 Catalogue of the English Fossils in his collection, published since his decease in 

 8vo, at London 17 29. 



Mr. Gabriel Fahrenheit, p.r. s. communicated, in N° 383 of the Philos. 

 Trans. A Table of the Specific Gravities of 28 several Substances, from hydro- 

 statical experiments of his own, made with great care and exactness; to which 

 he subjoined some observations on the manner in which his trials were performed, 

 with a description of the instruments in particular which he made use of to exa- 

 mine the gravities of fluids. To some of his experiments, which he thought 

 required a greater nicety, he has affixed an asterisk in his table, signifying such 

 to have been adjusted to the temperature of the air, when his thermometers stood 

 at the height of 48 degrees. This gentleman, who is well known by the repu- 

 tation of his mercurial thermometers, which he made with great accuracy, and 

 which are now generally used, was in England in the year 1724. 



Professor Peter Van Muschenbroek, of Utrecht, published in his Elementa 

 Physicae at Leyden in 8vo, 1734, a large table of specific gravities, which he 

 afterwards somewhat further enlarged in his Essai de Physique, in French, at 

 Leyden 1739, 4to. This table contains almost all the preceding ones, but with- 

 out the names of the authors from whom they were collected. Dr. D. has among 

 those which follow, inserted under this author's name, such experiments as he 

 had not before met with elsewhere, making use of the Latin edition as the more 

 correct, except in such articles as are only to be found in the French. 



Mr. John Ellicott, f. r. s. having an opportunity in the year 1 745 to examine 

 the weight of some large diamonds, he accordingly, with the utmost care, and 

 with exquisite assay scales, which very sensibly turned with the 200th part of a 

 grain, took the specific gravities of 14 of those diamonds, 4 of which came from 

 the Brasils, and the other 10 from the East Indies. These experiments he com- 

 municated to the president of the Royal Society, who caused them to be read at 



