Advertisements. 
7Vi 
tffcn Optical, Mathematical, and 
(henry porter,), " Surveying Instrument Makers, 
By Special Appointment to the Admiralty (H. M. Training Ship Britannia), War Office (Royal 
Military Academy, Woolwich), India Office, Royal Geographical Society. Crown Agents, for the 
Colonies, British South Africa Company, British North Borneo Company, the Peruvian Corporation, 
the Central, Borneo Company, African Exploration Company, Oil Rivers Protectorate, African 
International Flotilla and Transport Company, various Foreign Governments, &c., &c. 
New Pattern Alt=Azimuth Theodolite. 
With Portable Folding Tripod Stand, very light, designed expressly for the 
Traveller in rough Countries. Price £23 : O : O complete. 
Theodolites, Levels, Prismatic Compasses, Aneroid Barometers (with Scale 
of Altitudes), Sextants, Artificial Horizons, Drawing. Instruments, Plane 
Tables, Telescopes, Binoculars, &c. 
All these Instruments are specially manufactured for the African Explorer and Surveyor, and are 
- • such aTs we supply to the Royal'Geographical Society. Established 1765. 
CflSY & CO., * 7 , PALL MflLL, LONDON. 
