316 PHILOSOPHICAL TRANSACTIONS. [aNNO lOsG. 



the bellows, bear but 20 inches; and so all the rest must bear more or less, ac- 

 cording as they lie higher or lower: it is evident therefore, that there are as 

 many parts that bear less than 20 inches, as there are that bear more; and the 

 increase of pressure following an arithmetical progression, it is undeniable, that 

 all these pressures added together will do no more than one uniform pressure, 

 that would be equal to 20 inches every where. 



Having thus found the quantity of pressure caused by the mercury within the 

 bellows, we must remember that the pressure of the atmosphere within the 

 «ame bellows is equivalent but to 5 inches, as I observed in my first paper ; so 

 that we find that the inward pressure is equivalent only to 25 inches of mercury 

 in all. Now the pressure of the atmosphere on the outside is every where equal 

 to 27 inches (French) ; from whence it appears that the pressure without is 

 stronger than the pressure within. So that I had reason to say, that the bel- 

 lows standing upright must rather shut than open. 



Although I might observe some other things in his description, which will 

 increase the difficulty of opening the bellows, I forbear to speak of them ; 

 noticing only what is most material, and makes his perpetual motion to be alto- 

 gether impossible. As for the argument the author draws from comparing his 

 engine to an ordinary siphon ; I beseech him to consider what a diflference there 

 is between a siphon from which the water runs down at the bottom, and his 

 engine, which ought to draw up the heavy liquor into the highest part of the 

 instrument, and I doubt not but he will acknowledge the weakness of his 

 argument. 



yf short Examen of the Stones sent to the R. S. from Bern, of which an Account 

 is given in the last Transaction. By Frederick Slare, M. D. R. S. Soc. 

 N° 1«2, p. 140. 



Those who have made experiments in hydrostatics find all pure metals to 

 have specific and peculiar gravities. From this hint Dr. S. formerly endeavoured 

 to discover the nature of the calculus humanus, which he found to have no at- 

 tributes that are proper to a real stone ; and bringing them to a hydrostatic test, 

 he found them very different in their specific gravity, and very remote from an 

 equal proportion to their bulk of common stone, when weighed in water. 

 There is a standard of gravity so competent to all real stones, that where they 

 deviate from this standard, we have good reason to question those concretions, 

 whether they are stones or not. The standard of gravity for real stones he found 

 to be generally about 2 to l * of the common fluid. 



* Common stone however, ii to water, more accurately as 2 J to 1. 



