enabled to procure but two solitavy individuals. Th^s 

 notice is given wilh the view of inciting the attention 

 of those naturalists who may have better opportunities* 

 i>( examination tlian I had. 



PLATE XIV. 



T'^. 1, n. clodcJv>>. Tig:. 2, Section of Ae body <ijil VTcHicaUy, T^S'% 

 ijf.c'.'ion of tbq head of its fiataralsize,' 



jBcscription of a jHydrostatic BALA^^CB", hy wTiic^ 

 the svfcijic gravities of mbierals may he ascei'iai.'ei 

 withoid calciilntion. By Bevj. H, Coatesj M. B^ 

 Read June 16, 1818. Plate XV. 



The present instrument has arisen from one latel/^ 

 pieseiited to the Academy, in which tlie common steel- 

 yard is employed for this purpose. 



The object of the alteration is, without rendering 

 fhe instrument more complicateil, or more troublesome- 

 in its application, to save the labour and inconveni- 

 ence of calculation. By means of it the specific gra- 

 tity of a mineral may be ascertained in a few mo- 

 ments, and without pen and ink, or any other assist* 

 ance than a cup iy[ water. With the aid of the neat- 

 ness and convenience of the instrument on which it is 

 grafted, it is hoped to be a practical saving of time 

 and la])oul' to tlie mineralogist. 



The lever resembles that of a coi^jnion steelyard, 

 |3t^d is contrivei tff balaucc es^acily^ by maiiiug th^ 



