618 SEC. 15. GEOGRAPHY. 



3035a. Capt. George's Improved Portable Artificial 

 Horizon. Henry Porter. 



This combines the reservoir for holding the mercury with the trough for 

 observation, the two being cast in one piece of iron, with a stopcock to let the 

 mercury run from the reservoir into the trough and back again when not in 

 use. This instrument has a perfectly worked parallel glass floating upon the 

 surface of the mercury, thus giving a perfectly brilliant surface and protected 

 from the action of the wind ruffling the surface of the mercury during an 

 observation. This instrument combines the most perfect horizontal surface, 

 with exceeding portability (being less than one sixth the size of the ordinary 

 mercurial artificial horizon) and the greatest facility in use. 



3036. Ramsden's Great Theodolite, with other instru- 

 ments and apparatus, employed by Major-General Roy in the 

 trigonometrical survey. Royal Society. 



3037. Large Levelling Instrument by Gary. 



Royal Society. 



3038. Large Levelling Instrument by Troughton and 

 Simms. 



3039. Five-Inch Theodolite by Adams. Royal Society. 



SURVEYING AND OTHER INSTRUMENTS LENT BY 

 VARIOUS CONTRIBUTORS. 



3040. Theodolite of Early Form. 



School of Military Engineering, Chatham. 



3041. Complete Set of Instruments for Surveying in 



mountainous tracts : 



a. Square box, containing parallel rule, with diopters and tele- 



scope, compass and level. 



b. Surveyor's table. 



c. Three-legged stand with bronze head ; each leg in two parts, 



to be screwed together. 

 The whole set to be carried on a knapsack. 



Survey Office, Chris tiania, Norway. 



3041 a. Compass Binocular. 



Robert E. Barker, Clifton, Bristol. 



This combination will be of service to officers of the army or navy, also to 

 exploring parties, travellers, or tourists. With it the compass bearings of any 

 object in the field of the glass can be seen directly in the mirror attached. It 

 adds very little to the weight of the glass, can be fitted to any binocular, and 

 will readily go into the original sling case with it. Rough surveys maybe 

 made with it in positions where larger and more costly instruments would not 

 be available. 



