38 
President's Address. 
[Feb. 
in longitude between distant countries, and especially between England and 
India, by means of the electric telegraph. This has resulted in the cor¬ 
rection of the longitude of Madras, previously ascertained by very long 
and tedious astronomical observations, extending over many years, by 3F8 
seconds of time or rather more than half a mile of distance in this latitude. 
No addition has been made during the past year to the work described in 
the Report of the Survey for 187G-77, both the officers engaged, Major 
Campbell and Captain Heajviside, having been absent on furlough. Ano¬ 
ther question to which much labour has been devoted by the Survey is the 
establishment of bench-marks throughout several parts of the country by 
means of careful spirit-levelling. The vast importance of such marks for 
engineering works and especially for all plans of irrigation is manifest, and 
it is not inqrrobable that the scientific importance of the levels will increase 
greatly, as, in connection witli a series of other observations at tidal stations, 
they will afford data for determining whether changes in the elevation of 
land are taking place in different parts of the country. 
Amongst the numerous subjects to which the officers of the Trigono¬ 
metrical Survey have directed their attention, some of great interest have 
been described, at Genl. Walker’s suggestion, in the Journal of the Society 
for the past year, and it may fairly be hoped that the publication, in this 
form, of observations such as those made for the purpose of determining 
the mean sea-level in the Gulf of Cutch, may serve the purpose of making 
the results more widely known than if they were recorded only in an official 
report, whilst the Journal of the Society gains in interest and value by 
being made the medium of publication. The paper by Lieut. Harman, to 
which I have already alluded, on the results of measurements of the Assam 
rivers, will, I hope, be read this evening. 
Few plans for recording the advancement of any enquiry are more 
trustworthy than a comparison of the methods employed in delineating the 
results : careful observations require for their record neat and accurate 
drawing, and facility of reproduction. Thus the account given by Captain 
Waterhouse in our Journal of the various photographic methods employed 
in the reproduction of maps and plans, whilst dealing solely with the art of 
map printing, shews indirectly the great advance of the science of Geogra¬ 
phy in India, and the demand for more accurate knowledge of the surface 
of the country. The progress of the whole art of Government in India 
during the last thirty years, and the change from cordparative ignorance 
to more accurate knowledge, could not be better illustrated than by a compa¬ 
rison of the maps produced at the commencement of the period, and 
those now issued, and it may safely be asserted that the increase in the 
accuracy of the maps is at least equal to the improvement in map 
printing. 
