1(5 



Georg Butenschoen, Bahrenfeld- Hamburg. 



No. 2755. 



Georg Butenschoen, Bahrenfeld m. Hamburg. 



Mathematical and Mechanical Instrument Maker, 



exhibits a Travelling Theodolite, an Inclinable Levelling Instrument 

 and a number of pocket instruments. It would lead too far were we 

 to attempt to give a detailed description of all the instruments made 

 by this firm. The Pocket Levelling Instruments, invented and patented 

 by the exhibitor, the speciality of the firm, may, however, be explain- 

 ed in a few words. 



The instrument, which fits into a case and may be carried in the 

 pocket, is represented in the annexed illustration. It possesses the 

 special advantage that by its means, the spirit-level, cross-lines 

 and the object can be viewed simultaneously, the position of the 



bubble of the spirit-level 

 not being, as is the case 

 with the usual instru- 

 ments, controlled exter- 

 nally, but, by means of 

 a mirror placed at an 

 angle of 45 between the 

 ocular and the cross- 

 lines, through the tele- 

 scope, where it is viewed 

 together with the object. 

 The image of the spirit- 

 level appears magnified 

 in the ocular, whereby 

 the exactness of the adjustment is greatly enhanced. The instrument,, 

 by this arrangement, attains, with due regard to its size, considerable 

 powers and greatly surpasses the water-level which is still extensively 

 used. The necessary manipulation is very simple, so that those, who 

 are not accustomed to work with the telescope level, will find no 

 difficulty in becoming familiarized with its use. 



The business was begun on a small scale but rapidly worked 

 its way upwards. Mathematical and surveying instruments form the 

 principal objects of manufacture, but also nautical and astronomical 

 instruments are made. The instruments find a regular market in ail 

 European countries and meet also w y ith considerable demand in trans- 

 atlantic states. 



