186 Dr Traill on the Specific Gravity (fi' Sea^Water, 
ascertained by previous experiment, the bottle, thus prepared, 
was sunk to the requisite depth ; and after remaining there for 
half an hour or more, was drawn up and immediately secured. 
My experiments were carefully conducted by means of a deli- 
cate balance, and a thin flask, capable of holding upwards of 1050 
grains of distilled water, when its ground stopper was adjusted. 
A bottle of distilled water, and all the specimens of sea-water, 
were reduced to the same temperature, by being placed for many 
days on the same table, in a room without a fire ; and to pre- 
vent error from this source, each liquid was examined by a good 
thermometer previously to the experiment. The weight of the 
distilled water bearing the same ratio to the weight of an equal 
volume of the other fluids, as 1.0000 to the sought specific gravi- 
ties, is the simple formula from which the following table is de- 
duced. 
Table of Specific Gravities at Temperature 51° Fahr. 
1. Sea- water drawn from the surface, Lat. 47° 47' N. 
Long. 10° 40' W. - - = 1.0^77 
Ditto from the depth of 40 fathoms, ditto, ditto, = 1.0280 
3. Ditto from the surface, Lat. 37° N., Long. 9° W. 
off Cape St Vincent, - - rr 1.0281 
4. Ditto from the surface, Madeira, bearing NE. 
distance 16 leagues, - - r= 1,0284 
5. Ditto from the depth of 40 fathoms in the 
same spot, _ » _ — 1.0286 
6. Ditto from the depth of 36 fathoms, Lat. 26° N. 
Long. 64° W., during a voyage to Demerara, 1.0287 
7. ' Ditto from the surface, Lat, 22° 11' N., Lon- 
gitude not given ; but as it was in the same 
voyage as No. 6. it was probably more to 
the west, - - - 1.0289 
8. Ditto from the surface, Lat. 8° 20' N., Longi- 
tude not given ; but as the three last num- 
bers were obtained in the same voyage to 
Demerara, and this one, at my request, was 
taken when the Captain supposed that he 
would make land in a day or two, there can 
