Opinion on Hydrometers, by Dr. Hare. 149 
has a tendency to introduce, atatng: those who mannfactute 
er deal in spirit. 
he only evidence, of the comparative eligibility of the 
instruments laid before me, which was adduced in a form to 
which I feel my welt justified in lstentonr: was that of Mr. Jack- 
son, one of t venue officers of this port; on whose judg- 
ment and aay; I place great reliance. . This officer 
appears to prefer the instrument to which he has been accus« 
tomed ; and he demonstrated, that there was no inconven- 
ience in the use of it, adequate to justify’ its being exchang- 
ed for the hydrometers of Southworth, or Tucker, which 
were the only instruments placed in competition with ‘it. 
Had not the hiyadroih eter of Dicas been already employed, I 
should not have aarti it to that of Tucker, which ap- 
ars analogous in princ and is apparently very well 
made. The hydrometer o Southworth, although in design 
and execution, apparently less perfect than the other, for 1 
urposes of manufacturers and dealers, is recommended by 
its sinipbicity: It has only one weight ; and, in most cases, 
will answer, without any change of wei ht. The corree- 
tions for temperature, are made by adding or subtracting 14 
ps for every five degrees of temperature. 
and “ay they should be authorized to incur a n deaieesilli ex- 
pense, in the requisite investigations. 
Ihave been for some time engaged, in ascertaining the 
merits of some methods of determining gravities, ea a 
ree new. I intend, shortly; to lay the reouls 
the . 
Although iti it is possible, that, im practice, cnidsonete ob- 
Jections to these new instruments may arise ; I have no hesi- 
tation in saying, that they possess a very important charac- 
teristic, that of being so simple and obvious, in the principle 
their construction, that they may be tested at any time, by 
a pair of nor en or a scale ben's and that, like the last 
mentioned instrument, they furnish a mean of 
value of the article, easily comprehended and estimated, by 
those who are interested in the result: whereas the hydrome- 
ters, now used, afford indications, which must be taken upon 
trust, especially by the inexperienced. ~ 
