4 NATURE 
Mr. Pogson intends as soon as possible to continue 
his work, and the greatest praise must be given to this 
distinguished astronomer for his persistent efforts to 
complete the records of his Observatory. But what can 
be thought of a system of administration under which 
observations are reduced about half a century after they 
are made? If this were the only instance of such a 
monstrous delay it would be bad enough, but we seem 
destined to have another instance, no less flagrant. 
The late Mr. John Allan Broun finished his work at the 
Trevandrum Observatory in 1864, and as yet only the 
first volume of his reductions has seen the light. Here 
the Observatory has been discontinued, and we do not 
know that any one has come forward to complete the 
labours of Mr. Broun, so that the publication of the 
remaining volumes seems to be adjourned indefinitely. 
Surely there is something in this system which requires 
putting right. 
Mr. Pogson tells us in his introduction that the vertical 
force results were never entitled to any confidence, espe- 
cially before March 1853, when, for the first time, the 
needle was placed nearly perpendicular to the magnetic 
meridian, agreeably to the directions given in the report 
of the Royal Society. Our readers are probably aware 
that at the present moment a Committee of the British 
Association is engaged in discussing magnetic observa- 
tions, and they are anxious to bring together all reason- 
ably good determinations of the solar-diurnal variations 
of the three magnetic elements for as many places as 
possible. 
It may therefore be of interest, especially after the 
above remark by Mr. Pogson, to apply some sort of pre- 
liminary test to the Madras observations. I shall there- 
fore compare them with the similar results obtained at 
Bombay, and discussed by Mr. C. Chambers in his recent 
elaborate and excellent volume. 
In the following table we have in the first place a com- 
parison of the solar-diurnal variations of declination at the 
Colaba Observatory, near Bombay, andat Madras. For 
the purpose of this comparison it is unnecessary to give 
the scale values or to exhibit all the months. We have 
therefore limited our comparisons to a mean of the three 
months, November, December, and January, and also of 
the three months, May, June, and July. 
TABLE I.—Comparison of the Solar-Diurnal Variations 
of Declination at Bombay and at Madras 
Se Abe | eae dog {bea 
> ll as a5 Sell Ae ae 
Sse oF og £56 OFF On 
fa 2 = a = an 
h. m. h. m. 
Oo 12 +23 + 23 Oo 41 + 8 + 16 
I ;, aay / at 37 I ;, ar + 25 
2; + 4 + 44 255 = 35) ap Sis 
oe —12 + 46 3» —12 oo 
4» 50) su BH 4s — 23 + 34 
So» — 54 + 85 5» 50 + 60 
+4 — 67 +206 Os — 48 +120 
7 >> — 74 + 272 7» — 40 +129 
Sips iL +249 Sie: Su tb ON 
9» +48 +128 9 55 +10 + 21 
Io ,, + 33 = 2 Io ,, =e = 4] 
Titees — 26 —165 TDs, —10 -I01 
2; — 34 — 245 Toe ° —121 
113} 59 + 8 — 236 13 5, +12 —105 
ess +28 — 184 UAT, +14 — 76 
15 >, +31 — 105 T5 5, +22 = 49 
16) 55 +26 = 34 TO) ss +23 -— 12 
17 5; oO fe) 17 5, +12 ° 
78%; +1 - 6 TSiys +16 - 13 
LOW, +19 — 45 19) 5 +19 — 22 
2055 +17 — 48 20 4; +13 — 19 
OTe. +14 - 33 DIT aes + 9 - 9 
22565 +18 - 15 220s +10 fe) 
Pas +24 + 5 23») +10 + 8 
| Way 6, 1886 
Now it will, we think, be seen from Table I. that at 
both stations the type as well as the range of the solar- 
diurnal variation is very different for the two groups of 
months. It will likewise be seen that the peculiarities of 
the summer variation are very much alike at both sta- 
tions, and that the peculiarities of the winter variation 
are also very much alike. Thus the comparison is 
favourable to the accuracy of the observations at both 
stations. 
Let us now turn to the force components. In Table II. 
we have a comparison of the horizontal and vertical force 
variations at the two stations for the two months, June 
and December. 
TABLE I].—Comparison of the Solar-Diurnal Variations 
of the Horizontal and Vertical Force at Bombay and 
at Madras 
Bombay civil time Horizontal force Vertical force 
(noon = 12) June Dec. June Dec. 
hey pm: 
o 18 — 105 — 98 ae ato) +11 
1. i. = 96 = 15) Tei +9 
2» = 07) a $4 =k: 36 toyh9) 
3) irs — 94 > + 30 am 5) 
4 » — 92 — 64 + 36 cmt) 
By 2D = Se) Roe + 59. aS) 
6 55 =a 4-7 Teo: | + 95 + 3 
ah ae wi + 28 + 74 + 8 
Saar +101 ae, Cs} + Io + 28 
9 » +189 +161 — 80 720 
LO} ys + 287 +23 —153 -57 
Ti 55 + 302 +242 — 162 —61 
2 ee +278 + 204 —116 —19 
Bl op +214 +134 65 +6 
14 5; +120 + 66 = ity) +9 
Loe + 21 qe + 19 + 8 
16 ,, = e50) 27 eee a 7) 
7a ase — 105 65 ap 22 = 18 
18 ;, — 132 = 4 ap 
19 5, —12 86 ap 3} + 8 
20) |; — 124 — 105 ap it} + 6 
PAK 5p —1i21 SUG! + 2I ee et 
22 5; —119 111 + 31 +9 
23ers III — 109 + 34 +10 
Madras civil time Horizontal force Vertical force 
(noon = 12) June Dec. June Dec. 
h. m. 
o 4! — 309 — 284 + 923 + 666 
Wp — 299 — 245 + 543 + 697 
2a. — 268 — 226 te FSH) + 650 
Bae — 258 —218 + 515 + 529 
4 » — 243 — 197 + 558 ae 
5 ~ 236 ~ 159 a (O07 et no70 
Cae ap e+5) - 80 + 300 + 879 
7 5 an 9 ae they tr 250) ) chesog 
ES a5 + 365 +317 = G83 a 7) 
Ome, +658 +57 —1329 — 938 
ifoh = 5 +873 +740 — 1688 — 1247 
cle +876 + 730 — 1926 — 1043 
Tae +716 +580 — 163 — 1246 
13s + 483 + 354 — 1096 — 1304 
1A Gs +194 +160 — 389 = ye 
T5toee — 66 ar 1G + 60 33% 
16) 3: = 211 = Gi + 241 — 289 
Gh os — 281 — 185 + 30 a3} 
is) op — 319 — 256 + 426 1 75 
19) =338' = 326 Ho 555) 2 at te 
20s — 323 — 360 + 596 + 280 
21 es — 336 — 374 + 640 4- 376 
22 5; 1309) eat cee) ae See 
230 ~ 31r — 314 + 99t + 747 
1t will be seen from this table that at both stations and 
for both components the type for June is nearly the same 
as that for December, the chief difference being in range. 
Also that the type at the one station is very similar to 
that at the other. The most marked difference between 
the two stations is for the vertical force, the range of this 
element in December bearing a smaller proportion to its 
