NABER FE 
97 
THURSDAY, NOVEMBER 30, 1882 
THE INDIAN SURVEY 
General Report on the Operations of the Survey of India 
during 1880-81. 61 pp. Report, 93 pp. Appendix, and 
22 Plates. (Calcutta, 1882.) 
HIS Report for 1880-81 (the fourth since the various 
branches of the Indian Survey were amalgamated) 
shows as usual a good amount of useful work done in the 
year, and contains also many points of general interest. 
There were in all twenty-nine field-parties and six large 
head-quarters’ offices. The whole out-turn of work cannot 
be shortly stated, and the total cost is not given; but it 
appears that there were 22,765 square miles surveyed 
topographically, 6141 square miles in great detail, besides 
much minor and special work, also that eleven Revenue 
Branch parties surveyed 11,326 square miles at a cost of 
about 81,000/. 
The principal triangulation of India proper as designed 
by Col. Everest, has now been finished. The result is 
shown on a skeleton map, which is itself a wonderful 
sight. There is a continuous “chain” of triangles right 
round India proper, connected across by zazy meridional 
and east to west “chains,” the longest being from 
Mussoorie to Cape Comorin (say 1600 miles north to 
south), and from Chittagong to Kurrachee (say 1800 
miles east to west). Outside India proper there are five 
important extensions, viz. (1) to Kandahar and Khelat ; 
(2) over Kdshmir ; (3) up the Indus beyond Leh ; (4) up 
the Brahmaputra to Sudya; and (5) a coast ‘‘chain” 
from Chittagong to Tenasserim. This great work, now 
finished, is one of which India may well be proud. 
Certain important changes of procedure are being in- 
troduced in the general survey work, viz.: (1) All the 
topographical work is being brought to a uniform system ; 
(2) Fieldbooks are gradually giving way to direct plotting 
of detail in the field with advantage in speed of work and 
economy ; (3) Special riverain surveys will in future be 
made; (4) Local agency is being tried for detail work ; 
this last measure is expected to effect great economy in 
the survey of Burma, for which at present a staff of 2500 
men is taken from Calcutta and back again each season. 
Great difficulties often beset the parties in the wilder 
parts of the country. Many parts are extremely un- 
healthy, and the parties often suffer severely from fever, 
&c. In a few parts the roughness of the country, in 
others climatic conditions, render travelling exceptionally 
difficult, e.g. travelling in the hot wind across the 
“Rann” (great salt desert) of Katch is dangerous to 
both man and beast. In a few parts even in India 
proper, ¢.g. among the wild Bhils, the surveyors are 
looked on with suspicion and sometimes attacked. The 
greatest praise is due to men who carry out their field- 
work through such difficulties as these. 
In general a survey party now accompanies every 
military expedition ; thus some extension of geographical 
and. trigonometrical work was done in 1881 by parties 
sent with the Mahstid Wazirf expedition and with the 
troops at Kandahar. A curious difficulty has arisen in 
that the modern use of the heliostat in military signalling 
almost precludes its use for survey stations along with 
an army. 
VOL. XXvII.—No. 683 
Self-registering tide-gauges with 5 feet barrels have 
been set up at fourteen places, and have worked well as 
a whole. Tide registrations (mostly from older instru- 
ments) for twenty-three years in all have been analysed 
by the harmonic analysis at enormous labour. The dis- 
cussion shows (for the first time) the existence of a 
“lunar fortnightly tide” as had been expected from the 
tidal theory. Tide-tables for 1882 were published for 
fifteen ports. 
The tidal stations of Madras and Bombay have been 
connected by “levelling” right across the peninsula with 
the curious result that the mean sea-level at Madras 
appears to be 3 feet above that of Bombay. The cause 
of this is still a subject of inquiry. It is really a very 
curious question. Thus, it is said that “there can be no 
sensible differences of level,” ze. as determined by 
levelling, ““ because the causes by which they would be 
produced must equally affect the spirit-levels of the in- 
struments and the water-levels of the ocean,” so that had 
the “levels been carried, without error, along the coast 
line from Bombay . . . to Madras, they must have shown 
identity of sea-level, &c.” On the other hand it is also 
said that “the Western Ghats are a source of attrac- 
tion, which, if not counteracted, must raise the sea-level 
at Bombay no less than 31 feet above the mean sea-level 
at Madras.” The difference (which should be zero?) is 
attributed to observation-error, and chiefly to the effect 
of the oblique sunlight illuminating the two ends of the 
instrument-bubble unequally : thus it is said that an error 
of only 1°2 seconds in levelment (a very minute quantity) 
at even one-fourth of the instrumental stations would 
produce the total error in question. 
An interesting improvement has been introduced in the 
engraving branch, viz. in steel-facing the copper-plates, 
and is said to be very successful. Apparently engraving 
on copper is still largely used (as also in the British 
Ordnance Survey), but it would seem that this tedious 
and costly process must give way to some of the rapid 
and cheap photographic processes. The Indian Survey 
is also utilising the latter very largely, with the wonderful 
result that ‘‘at present publication may, and frequently 
does, follow the survey in a few days.” There is a curious 
instance of the possible saving in departmental manufac- 
ture, in that about 334/. has been saved by making up 
collodion in the office instead of purchasing it. 
Of underground temperatures it is noted that at Dehra 
the maxima occurred at the three depths, 674, 12°8, 25°6 
feet, about September 20, October 15, and November 15 
respectively (the maximum in the air being probably in 
June ?). 
An extraordinary outburst of solar spots, covering 630 
million square miles, was observed to take place on July 
25, 1881, within a period of thirty-seven minutes ; it is 
rare that so grand an outburst is so closely located 
in time. 
The Indian Survey was well represented at the Venice 
Geographical Exhibition. The whole collection sent 
seems to have excited great interest, especially the tidal 
instruments which were connected with the Main Canal 
so as to be shown in actual work. This exhibition brought 
to light a striking difference in recent practice of con- 
struction of instruments in England and on the Continent 
in that recent improvements in graduating circles are so 
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