126 Ludwig Tesdorpf, Stuttgart. 



6. Scale G on the base-plate P, with controlling divisions reading to 

 1 millimeter and vernier, serving as guide for the sliding-piece K with needle 

 apparatus. 



7. Projection triangle R, running on wheels with automatic spring 

 stop. By means of this triangle the oblique distance adjusted by scale A is 

 projected with the aid of a vernier upon scale P. 



Note I: The vertical scale of this triangle, which reads to 1 millimeter, 

 is not numbered, on account of the great variability of the elevation; heights 

 from 10 to 10 millimeters may, however, conveniently be marked upon the 

 celluloid strip let in for this purpose with lead-pencil and these notations are 

 again easily removed. This vertical scale may be used without changing the 

 notation for differences in height, provided the differences of level between two 

 points of observation do not exceed 15 meters (being 15 millimeters of the 

 scale divisions). 



Note II: The projection triangle has at its underside a lug projecting 

 downwards which fits into a cavity in the sliding piece K; this causes the 

 needle apparatus to describe always the same path along the divided ruler F. 

 The readings of scales F and G must, therefore, always agree. 



8. Sliding-piece K is attached to the needle apparatus. The latter 

 serves to transmit the projection of the distance taken by scale A to the 

 drawing paper. 



9. The wheels. By means of these and a box bubble placed within the 

 pillar the apparatus is levelled. 



Note: The three axes of rotation of the wheels intersecting in the 

 common center of the apparatus, which lies exactly vertically below the center 

 of the telescope axis and at the front edge of the base-plate, the apparatus 

 rotates freely round this point (the zero point of the adjustment). By means 

 of a break attached to one of the wheels the position of the apparatus may be 

 fixed at any moment. 



10. Centering ruler. This serves to maintain an unchanged adjustment 

 of the instrument while several readings are being taken from one point. This 

 ruler, which has a round projection and diaphragm, is held down upon the 

 paper with the right hand. While taking hold of the pillar with the left hand 

 and moving the instrument with its corresponding round cavity towards the 

 ruler the apparatus may be freely rotated round this center. 



Note I: The center of the round cavity, into which the centering-ruler 

 is inserted, lies exactly vertically below the center of rotation of the axis of 

 the telescope. 



Note II: When all the verniers are in their zero positions, then also 



1. the edge of the triangle E must coincide with that of the rotating 

 vernier of the sliding piece B. 



2. the needle point of the sliding piece K must be exactly above the 

 center of the round cavity at the front edge of the base-plate P. 



The under- structure : Principal parts: Stand with Tesdorpf 's Tripod 

 Levelling Arrangement, clamp and micrometer levelling adjustment with hori- 

 zontal tribrach base-plate. 



Circle: 10 centimeter diameter, reading to 1/2 degrees, with 2 verniers 

 reading to 1 minute. 



