620 SEC. 15. GEOGRAPHY. 



3046a. Dumpy Level, of improved construction. 



Joseph Casartelli. 



With graduated circle, for taking horizontal angles, and ball-and socket 

 motion greatly facilitating its adjustment, especially on hilly or uneven ground, 

 and saving the wear of the adjusting screws. The instrument being made of 

 hard gun-metal, and the centre being long and accurately ground, renders it 

 little liable to derangement. 



3047. Theodolite with 3 inch circle. 



Messrs. Troughton Sf Simms. 



The telescope is of the bent form, having a small rectangular prism in the 

 axis. The light received by this prism is turned through the axis of the 

 instrument, and an image of the object is formed outside the pivot. By this 

 construction the instrument may be kept low, and possess at the same time 

 considerable optical power. 



3O47a. Five Inch Theodolite. Joseph Casartelli. 



In making this theodolite the object has been to reduce the number of 

 parts and simplify the construction. It has double conical bearings to the 

 axes, with a ball-and-socket adjustment, and spring verniers to the altitude 

 circle, producing an easy and smooth motion. The whole is made of gun- 

 metal. 



3047b. Travellers' Theodolite and Stand. L. Casella. 



3O47c. Travellers' Theodolite and Stand, with telescope 

 in centre. L. Casella. 



3047d. Gary's Improved 5-in. Theodolite, with im- 

 proved rack adjustment to cross webs of eye-piece, and improved 

 form of tripod foot. Henry Porter. 



3048. Theodolite (10- 5 in.), in which the vertical arc is 

 jointed on an ordinary sector, and covered with a variety of scales. 

 Made by Sissons, London. Major M. L. Taylor, R.A. 



3049. Repeating Theodolite, horizontal circle 14 cm. in 

 diameter, vernier 1, sliding rule 30" specified, glass covered tele- 

 scope, 12 lines free aperture, magnifying 25 times, vertical circle in 

 1, sliding rule I/ specified. Level to arrange the telescope in two 

 positions, telescope for penetration, and to lie down. 



A. and R. Hahn, Cassel. 



Besides the addition of the movable level to the telescope, this instrument 

 possesses a new arrangement for its vertical movement. A small female 

 screw with right and left threads on opposite sides is inserted near the base 

 of the bearer. Corresponding to these threads are male screws tightly fastened 

 to the bearer, and, by turning the female screw to the inner or outer side, 

 the height of the telescope is increased or diminished. 



3050. Universal Theodolite (Bende's] construction), hori- 

 zontal circle 12 cm. diameter, vernier J, sliding rule 30" specified, 

 repetition and glass covered telescope, 15 lines free aperture, mag- 



