6 Ona New Method of recording differences of Declination. 
I shall now present a few measures of the sun’s diameter, in 
which it must be observed that only relative quantities are ob- 
tained. Taking the N. A. as accurate on any one day of those 
indicated in the observations, we found the power of the new 
apparatus to trace the apparent changes in the sun’s diameter. 
This is not yet absolute work. 
Observations of the © Diam. Cin: Obs. Sept., 1850. 
Obs. Diff. 
omp. 
Sept. 3, 1906-68 1906-40 +0°28 
- 4, 1907-40 190680 +0-60 
5, 1906-82 1907-40 —0 
6, 1907-62 1907:80 —0°18 
%; 1906-73 1908-40 —1) 
9, 1910-74 1909-40 + 1:34 
12, 1911-58 1910-80 +-0:'78 
13, 1910-17 1911-40 — 1:23 
16, 1912-44 1913-00 — 0-56 
17, 1912-65 1913-40 —0°75 
19, 1914-74 1914-60 -+0°14 
20, 1916-00 —«1915-20 40:50... 
21, 1916-62 in. ee 
1851. . 
May 15, 1900:10 1900 02 -++0:08 
22. 1897-80 1897-60 40-20 
24, 1897-46 1896-80 — 0-66 
96, 1896-07 1896-20 —0-13 
The work in 1850 was measured with the defective microme- 
ter, and I attribute the increased discrepancies to this cause, rath- 
er than to any inaccuracy in the observations or’records. ~ 
On the application of the principle already explained, of inter- 
mingling the observations of two different nights, most of the 
arge discrepancies which had for a long time annoyed me, and 
which I felt were due to imperfections in the micrometer (but 
which I had not hitherto been able to demonstrate) all disap- 
peared, and the results have since exhibited the most surprising 
harmony. I shall present only a few specimens of the work 
done, as a more full and elaborate report will be made hereafter. 
Observations of June 16th and 17th, 1851. 
16th. 17th. ~ Diff. 
Seconds. 
Observer, M. ¢ BootistoB.A.C. 4969 L. 6060 6064 0004 0016 
.t4 0 +852 | 
L. «Corone 6508 6420 0088 
M. 4706 3397 3288 0109 0 -336 
se M.« Bootis 8877 8687 0190 0 “760 
“ M. 4933 8882 8663 0199 0-796 
«“ L. 5120 1430 1268 0162 0-648 
‘6 - LiaSerp. 2245 2252 0007 0 ‘028 
5 ae pao ee 
0 418 
a ie See ees 
