660 
ME. AIET’S ACCOUNT OF THE COXSTEHCTIOX OF 
The work which obviously was first to be undertaken, was the preparation of ther- 
mometers. It will be convenient here to describe all that was done, to the time of 
Mr. Sheepshanks’s death. 
Thermometers were procured, generally in Series of twelve at a time, and each Series 
was distinguished by a letter or mark ; as A, B, C, Flat S, Flat Bore, Flat Notched, Bound 
Bore, Bound Notched, Long S, Bent. After all destruction by breaking, the number of 
thermometers still in my hands is 66. It was, I suppose, the intention of !Mr. Sheep- 
shanks, that each of the Standards which he proposed to construct should be accom- 
panied by a thermometer. Of these thermometers, a few were never examined at all ; 
but the greater part were examined, some for the freezing-point, some for the boiling- 
point, some for the subdivision, some for two or all three of these elements. Some were 
merely compared -with others of the series whose errors were determined by the original 
process (as, being intended for use through a limited range of temperature, they did not 
admit of independent determination of the boiling-point). 
The following thermometers, still remaining, were completely coiTected by the original 
process:-— A, 2, 5, 6, 8, 9; Long S, I, 2, 3, 6. The following were coi-rected by com- 
parison :--B, 4, 6, 6, 7, 8, 9, 10; C, 1, 2, 4, 6, 7, 8, 9, 10; Flat S, 1, 2, 3, 5, 7 (aU by 
comparison with A, 8, 9) ; Flat S, 6, 8 ; Flat Bore, 1,2; Bent, I, s ; also Bailt’s A (by 
comparison with others of the A series) ; Flat S, 9, 10, 11, 12 (by several of the A series 
and several of the Long S series); Bent, 0 Notch, 2 Notches (by comparison with the 
whole of the A series and the whole of the Long S series). The thermometers described 
as Bent 0 Notch and Bent 2 Notches are otherwise marked B and L, and are the ther- 
mometers which were inserted in the quicksilver trough, and on which in fact almost 
the whole of Mr. Sheepshanks’s operations in the comparison of his own standai'ds 
depend, so far as they are influenced by temperature. In some few instances, how- 
ever, the temperatures depend on I and s (bent thermometers ufith small bulbs which 
were inserted in holes in the bars). The freezing-points and the inequality of gradua- 
tions of L, B, /, s were determined independently, but not the boiling-points. 
I am inclined to think that the papers containing some of the early comparisons of 
thermometers have never reached me. Thus it would appear that for j\L'. Sheep- 
shanks’s “ Statement,” dated 1848, July 18, some comparisons of the Ordnance Bar 
Thermometers and of Baily’s Thermometer A must have been made ; but I find none, 
in the papers which I possess, anterior to 1855. Even for the important thermometers 
L and B, I find no comparisons anterior to 1850. In one of Mr. Sheepshanks’s papers 
I find mention of “ two good old thermometers,” and I conjecture that comparisons had 
been made with some thermometers supposed to possess superior authenticity. 
It would seem that, as soon as some progress was made in the preparation of thermo- 
meters, Mr. Sheepshanks proceeded to determine the value of one new bar, in terms of 
the Lost Imperial Standard. The bar first employed for this purpose was called by him 
“ Brass 2.” This bar was compared with Shuckbuegh’s Scale, the Boyal Society’s 
Standard, and the Ordnance Standards, and with others not essential to the present 
