102 
Prof. Forbes’s Letter respecting two Papers 
Table II. Table III. 
Thermometer. 
Barometer. 
Log. 
Diff. 
Log. 
Diff. 
Log. 
Diff 
0 
0 
In. 
50 
0*00000 
50 
0-00000 
31 
0-01424 
49 
0-00094 
51 
9-99906 
30-9 
0-01248 
48 
0-00190 
52 
9-99811 
8 
0-01143 
47 
000285 
53 
9-99717 
7 
0-01002 
142 
46 
0-00380 
54 
9-99623 
6 
0-00860 
45 
0-00476 
96 
55 
999529 
5 
0-00718 
44 
0-00572 
56 
9-99434 
94 
4 
0 00575 
43 
0-00668 
57 
9-99341 
3 
0-00432 
144 
42 
0-00764 
58 
9-99248 
2 
0-00289 
41 
0-00861 
59 
9-99154 
1 
0-00145 
40 
0-00957 
60 
9-99061 
30-0 
0-00000 
39 
0-01053 
61 
9-98969 
29-9 
9-99855 
38 
0-01151 
98 
62 
9-98875 
8 
9-99709 
37 
0-01248 
63 
9-98783 
92 
7 
9-99563 
36 
0-01346 
64 
9-98690 
6 
9-99417 
146 
35 
0-01444 
65 
9-98598 
5 
9-99270 
34 
0-01541 
66 
9-98506 
4 
9-99123 
33 
0-01640 
67 
9-98414 
3 
9-98075 
148 
32 
0-01738 
68 
9-98323 
2 
9-98826 
31 
0-01837 
69 
9-98231 
1 
9-98677 
30 
0-01935 
70 
9-98140 
29-0 
9-98528 
150 
29 
0-02033 
71 
9-98049 
28-9 
9-98378 
28 
0-02133 
100 
72 
9-97958 
8 
9-98227 
27 
002232 
73 
9-97867 
7 
9-98076 
26 
0-02331 
74 
9-97777 
90 
6 
9-97924 
25 
0-02432 
75 
9-97686 
5 
9-97772 
152 
24 
0-02531 
76 
9-97596 
4 
9-97620 
23 
0-02630 
77 
9-97506 
3 
9-97466 
22 
0-02730 
102 
78 
9-.97416 
2 
9-97313 
21 
0-02832 
79 
9-97326 
1 
9-97158 
20 
0-02933 
80 
9-97237 
28-0 
9-97004 
154 
XVII. Letter to Richard Taylor, Esq., with reference to two 
Papers in the Philosophical Magazine for January^ 184;0. 
By James D. Forbes, Esq.., F.R,S.S., L, -Ed., <^c. 
My dear Sir, 
TN order that your readers may be aware why I do not 
answer Mr. Potter’s animadversions in the January Num- 
ber of the Philosophical Magazine, I would request you to 
insert the following letter which I addressed to him after 
reading his communication. 
“ My dear Sir, « Edinburgh, Jan. 8th, 1840. 
“ I have read with some pain, and at least equal surprise, 
some observations by you on photometry, stated to have been 
