i ae 
To make it ready for obfervation, it is to be fufpended either 
on its ftand or on a hook, and holding it inclined, the ftop-cock 
is firft to be opened, afterwards the air-hole, and then it is to be 
let down very gently to its perpendicular direction. The fcale 
will fhew truly the {tate of the barometer. 
Ir any accident or fhake fhould caufe more mercury to flow 
out of the bafon than enough to fill it to the ftandard height, 
the adjuftment may be repeated as often as thought neceflary by 
only inclining the barometer, and forcing mercury from the 
bag into the bafon. It will be proper to obferve the height of 
the mercury by the fcale at each trial, and when it ftands at the 
higheft the barometer is properly adjufted. If it can be hung 
truly perpendicular, either by bracing it to its own ftand, or by 
fixing it to a firm poft, there is no occafion to difturb it for a 
new adjuftment ; the mercury may be forced into it as it hangs, 
and be fuffered to find its proper level by overflowing. This 
may be found convenient for obfervations in the houfe; if it 
fhould be preferred to ufe it as a barometer of the common con- 
ftruction, it is only neceffary to adjuft it once, and fhut the 
ftop-cock. 
TueE two boxes of this barometer may be made of box-wood 
or ivory of any convenient fize that may anfwer beft to render 
them portable. The diameter of the bafon may be very much 
reduced, as the accuracy of this inftrument does not depend on 
its fize. It need not be much larger than may be conveniently 
held in the hand, as the head of a walking-cane. If the tube is 
neatly mounted in a drawn brafs tube it may be enclofed within 
the 
