j22 Progress of the Trigonometrical Survey. [No. 2, 
connexion with the Superintendent of the department, and also with 
the field parties whose computations it has to revise and collate. 
21. The distant location of the computing office had entailed the 
formation of a small office at Head Quarters under the superintend- 
ence of J. B. N. Hennessey, Hsq., first Assistant Great Trigonome- 
trical Survey, composed of native Surveyors, and newly joined Sub- 
Assistants, who thus had an opportunity of being rigorously trained 
in the theoretical portion of their new duties. ‘This little office has 
lately completed the triplicate manuscript copies of the General 
report of the north-eastern longitudinal triangulation, between 
Dehra Dhoon and Purneah, in two thick imperial volumes; it has 
also been employed in revising the computations of the mountain 
triangulation of the north-west Himalaya Series, computing 3 
volumes of the report of the Levelling operations, and preparing the 
triplicate general report of the Trans-Indus Frontier Survey ; also 
in supplying elements, examining candidates, instructing new assist- 
ants, and other current work. 
22. The Drawing Office, under superintendence of W. H. Scott, 
Esq., Civil Assistant Great Trigonometrical Survey, has been chiefly 
employed in compiling maps of Kashmir and Ladak, from the plane 
table sheets sent in by Captain Montgomerie. The first of these 
large maps has already been transmitted to the Home Government, 
the second is well advanced. ‘Ten original preliminary charts of the 
triangulation in different parts of India have been forwarded for the 
use of the Surveyor General’s Office, and duplicates have been pre- 
pared for the Geographer to the Secretary of State for India. Tri- 
plicate charts have also been constructed for the manuscript volumes 
of the General Report. 
23. Between the completion of a Survey, in this country, and its 
publication, a long interval invariably elapses, during which even 
the Supreme and Local Governments are without access to valuable 
information, acquired but unimpartible, because of the costliness of 
manuscript maps and the time occupied in their construction. I 
have therefore been induced to attempt to employ photography for 
making rapid copies of our maps and charts, as a temporary substi- 
tute for the final engravings. This process has of late years been 
extensively adopted in the Ordnance Survey of Great Britain for 
reducing maps, as a substitute for the pentagraph. Two complete 
