642 
ME. AIET’S ACCOTJXT OY THE COXSTEHCTIOX OF 
o incli. 
1844, Jan. 2, from 20 comparisons at temperatm'e 43-21 Fahe., by 0-000564 
3, from 20 comparisons at temperature 38-20 Fahe., by 438 
4, from 20 comparisons at temperature 40-90 Fahe., by 699 
5, from 20 comparisons at temperature 46-34 Fahe., by 664 
6, from 20 comparisons at temperature 50-20 Fahe., by 637 
Mean by 100 obseiTations . . . 0-000600 
The Ordnance Bar lA compared with the middle 3 feet of the Eoyal Astronomical 
Society’s scale. It appears that the Bar lA was put in the place of the Eoyal SocietA-’s 
scale. The bar is notched at each end to half its depth, and the defining points are upon 
gold pins in the surfaces thus exposed. In the fii-st and second series, the u-on bar was 
laid on Bvo semicircular brass pieces 18 inches apart (not on rollers), in the same manner 
as when the bar was compared with the Imperial Standard *. In the third, fomth and 
fifth, it was placed on rollers. A doubt on the temperature exists, for the following 
reason. After the comparisons had been made. Colonel Colby informed ^Ii-. Bailt that 
the thermometer of lA gave indications too Ioav by 1°. Mr. Bailt however states that 
in the first five comparisons the thermometer of 2A was used. Yet the simultaneous 
readings of thermometers seem to make it probable (but not certain) that the thermo- 
meter of lA was really employed. If so, the mean temperatui’e m the following Table 
ought to be increased 0°-5. The Ordnance Bar lA is longer than the Eoyal Astrono- 
mical Society’s scale, — 
Q inch. 
1844, Jan. 7, from 20 comparisons at temperature 47-32, by 0-001300 
8, from 20 comparisons at temperature 43-82, by 1754 
. 9, from 20 comparisons at temperature 42-62, by 1999 
10, from 20 comparisons at temperature 41-85, by 2067 
11, from 20 comparisons at temperature 43-10, by 1872 
The Ordnance Bar 2A compared Avith the middle 3 feet of the Eoyal Astronomical 
Society’s scale. In the first two series, the bar Avas supported on its semicircular brass 
pieces ; in the others, on rollers. The thermometer of 2A was undoubtedly employed. 
The Ordnance Bar 2 A is longer than the Eoyal Astronomical Society’s scale, — 
„ ^ inch. 
1844, Jan. 12, from 20 comparisons at temperature 43-72, by 0-002108 
13, from 20 comparisons at temperature 44-60, by 2035 
14, from 20 comparisons at temperature 43-52, by 2148 
15, from 20 comparisons at temperature 40-72, by 2519 
16, from 20 comparisons at temperature 36-97, by 2958 
* Eoyal Astronomical Society’s Memoirs, vol. ix., and Measure of the Base on Lough Fojde, 
