<_<. © 
160 REPORT—1857. 
and after these dates in the neighbourhood, making a complete year, less 21 
days. Again, in precisely the same locality, from the 7th of September 1853 
to the 19th of July 1854, to which have been added the six first days of Sep- 
tember, and one day, the 20th of July, during which the ship was in the im- 
mediate neighbourhood, making a second complete year, less 42 days. The 
ship returned again to the same spot on the 27th of August 1854, and 
remained four whole days, for which the hourly register gave a mean tempe- 
rature of 39°-448, serving as a fair guide in estimating the temperature of the 
last eleven days of August, which accordingly has been assumed to be 39°448, 
thus reducing the interval in the last year to thirty-one days. 
To fill up the interval of twenty-one days’ absence in 1853, the mean tem- 
perature of these has been assumed at something between the decades last 
preceding and first following that period. Thus, the first ten days of August 
giving a mean of 38°441, and the first ten of September giving a mean of 
32°146, the second and third decades of August have been assumed as 37° 
and 35° respectively. In the same manner, to fill up the interval of thirty-one 
days in the summer of 1854, the second decade of July giving a mean of 
38°-287, the mean of the last cleven days is assumed to be 39°. The last 
eleven days of August having been caleulated to give a mean of 39°448, as 
already stated, the intervening two decades can, without much risk of error, 
be assumed at 40°. 
The thermometers used throughout the period of observation were made 
by Adie and Co. of Edinburgh, in February 1848 ; and having been returned 
to the Hydrographer’s Office, Admiralty, in April 1855, I have no doubt 
some of them could be obtained there, if required for comparison with any 
acknowledged standard. There were six of them, numbered from 10 to 
15, and remarkably alike in appearance and size. To each was attached a 
graduated glass scale, on which, besides the number, was cut the maker’s 
name. On application at Messrs. Adie’s establishment, Edinburgh, I ob- 
tained the following information as to their mode of construction :— 
“ For spirit thermometers constructed February 1848,— 
Before use, colourless alcohol, sp. gr. *79465. 
Before use, coloured BS po ee 
After use, * 4 » °79541. 
Points fixed from standard mercury thermometer 62° and 32°. Seale then 
run down to —56°.” 
They were on several occasions exposed together to different degrees of 
cold, and were very uniform in their indications down to the lowest tempera- 
tures registered. Subjoined is a table of thermometers compared (p- 161). 
It appears from this Table that five of the instruments by Adie indicated 
a mean of 35%5 nearly as the freezing-point of mercury, whilst that by Cox 
of Devonport stood at —41°, and that by Pastorelli at —48°. 
Pastorelli, No. 419, had an error of —1°5 at the freezing-point of water; 
and at our lowest temperature its indications were 13° below Adie’s. 
Cox’s thermometer, No. 1, had an error of 2° at the freezing-point of water, 
but at lower temperatures corresponded much more nearly with Adie’s. Like 
Pastorelli’s, however, it had the disadvantage of a heavy box-wood scale, pre- 
venting it from indicating rapid changes of temperature, which the glass scales 
of Adie’s instruments permitted. Both these were rejected for ordinary use. 
The mercurial thermometer used as a standard was Pastorelli, No. 406. 
This also had a heavy box-wood scale, but I believe was otherwise a good in- 
strument, and, if sufficiently long exposed to a uniform temperature, could 
be trusted as low as 32° below. the zero of Fahrenheit, At that point the 
