182 Mr Sang's Improved Theodolite Adjusbnent. 



and practically. True, some able friends of the cause have supposed 

 the ancient wines to be mostly intoxicating. But I rest, and always 

 have rested, its support on very different grounds than the per cent. 

 of alcohol in the wines of Syria and Palestine. But this is a point 

 irrelevant to the present paper, and therefore I waive it. To find 

 out the exact truth should be the object of every scientific investiga- 

 tion, however it may affect opposing opinions. — American Journal of 

 Science and Arts, vol. xlvi. No. II., p. 249. 



Description of an Improved Apparatus for Levelling Small 

 Theodolites* By Mr John Sang, Land-Surveyor, Kirkcaldy. 

 "With a Plate. Communicated by the Royal Scottish So- 

 ciety of Arts.* With a Plate. 



A theodolite of the common construction is levelled by 

 a series of alternate adjustments of two pairs of screw^s, 

 each adjustment requiring both hands of the operator ; its 

 plate is prevented from moving in azimuth by the same 

 screws, which have to be gradually tightened at each step 

 of the process, until, when the adjustment is completed, the 

 screws have also obtained the tension proper to keep the in- 

 strument steady. The operation requires some address, and 

 occupies a considerable time. By the improvement now de- 

 scribed, only one hand is required to regulate each level, and 

 the instrument is kept steady without tightening the screws, 

 so that both levels can be adjusted at the same time, and more 

 rapidly. It gives the same facility as the apparatus of three 

 screws, sometimes applied to large instruments, whose weight 

 is enough to resist shaking in azimuth. 



A (see P. II.) is a part made fast to the legs of the instru- 

 ment. It has two sockets at B B, and a box at C for holding 

 a cylinder containing a screw-nut. The box C is not well 

 seen in the drawing ; it is similar to the other one marked G. 



The part D has an axis E, working in the sockets B B, 

 each end of the axis is a double cone, carefully fitted into the 

 sockets, and tempered by the screws b b. It has, at right 

 angles to this axis, two sockets F F similar to those in the 

 lower part, and it has also a box at G, holding a cylinder con- 

 taining a screw-nut. 



* Read before the Society _, 8th January 1844. 



