I4S Defcr'tption of a Mercurial Air-holder. 



I examined the bones with confiderable attention, and I 

 found that there was adhering to the furface of many of 

 them, a fubftance which refembled the fpermaceti I have 

 before defcribed in the Philofophical TranfaAions for the 

 years 1794 and 1795. 



I have to add, that this cavern was difcovered about two 

 years ago by accident, and that no fatisfa6lory reafon has 

 been given for this lingular accumulation of human bones. 



XI. Defcription of a Mercurial Air-holJer, fuggejled hy an 

 Infpedion of Mr. IVatfs Machine for coniaining Factitious 

 Airs. ^ William Clavfield *. 



OEVERAL modes of counteradling the preffiire of a de- 

 creafing column of mercury having been thought of, in con- 

 junftion with Mr. W. Cox, the following was at laft adopted 

 as the mod fimple and effeftual : 



Plate V. Fig. i. reprefents a feftion of the machine, which 

 confifts of a ftrong glafs cylinder A, cemented to one of the 

 fame kind B, fitted to the folid block C, into which the glafs 

 tube D is cemented for conveying air into the moveable re- 

 ceiver E. 



The brafs axis F, fig. a, having a double bearing at a, a, 

 is terminated at one end by the wheel G, the circumference 

 of which is equal to the depth of the receiver, fo that it may 

 be drawn to the furface of the mercury, by the cord b, in one 

 revolution ; to the other end is fitted the wheel H, over 

 which the balance-cord c, runs in an oppofite diredlion in 

 the fpiral groove e : a front view of the wheel H is fliown at 



Fig- 3-. 



Havinc loaded the receiver with the weight I, fomethinf 

 heavier than may be neceflary to force it through the mer- 



* From an ingenious work lately publifhed entitled, Rifiarcbis Che- 

 mical and Philofopbicnt, cbii-fiy conctining niirous Oxjei or tUphlogijIi rated 

 nitrous Air, and its Rfjpiration ; by Humpbrty Dn-jy, Sn[>ain!tmdent of the 

 Medkal Pneumatic Injlitution. — This apparatus was firft defcribed in the 

 Tiiird Part of Dr. lieddoes's Conridcrations, but it has fince received feme 

 improvements. 



cury. 



