III. SURVEYING. 759 



3055. Compass Theodolite, a representation of an instru- 

 ment invented by the exhibitor, for observing, with a microscope, 

 the exact position of the magnetic needle. 



Prof. Joseph Schlesingcr, Vienna. 



3064. Cross-Staff, with box-level. 



Z'unmcr Brothers, Stuttgart. 



This instrument, cross-staff, with iron rod, angular mirror, and box-level, 

 serves for setting out right angles, made entirely of metal ; on stony ground 

 or in frosty weather it is preferable to the cross-staff with wooden pole. 



3065. Reflecting Hypsometer. 



Zimmer Brothers, Stuttgart. 



The cross staff and mirror hypsometer. 



The cross staff serves likewise for marking right angles and drawing per- 

 pendiculars. 



The mirror-hypsometer is used for measuring the height of trees, &c. 



These instruments are particularly useful for foresters and agriculturists, 

 on account of their being easily carried about. 



(See " Holzmessekunst," by Prof. Dr. Baur, Hohenheim). 



3068. Hypsometer (therino-baronieter), graduated in ^^ths 

 of a degree centigrade, and in millimetres representing the 

 corresponding tensions of aqueous vapour. 



W. Haak, Neuhaus am Renmveg, Thuringen, 



3068a. Improved Hypsometer, large, with thermometer 

 for the exact measurement of heights by the vapour of boiling 

 water. L. Casella. 



3O68b. Hypsometer, small, for travellers, with thermometer, 

 for the exact measurement of heights by the vapour of boiling 

 water. L. Casella. 



3069. Hypsometer for levelling. To ascertain elevations up 

 to 500 metres by observing the boiling point of water. 



W. Haak, Neuhaus am Rennweg, Thuringen. 



3070. Hypsometer for levelling. To ascertain elevations up 

 to 4,550 metres by observing the boiling point of water. 



W. Haak, Neuhaus am Rennweg, Thuringen. 



3071. Apparatus constructed for observing the boiling point 

 of water, in the use of hypsometers. 



W. Haak, Neuhaus am Rennweg, Thuringen. 



309O. Land Surveying Apparatus, of simple construction, 

 by A. Geppert, completed by F. Miller. F. Miller, Innsbruch. 



This apparatus, chiefly designed for work requiring no particular exactitude, 

 and which a beginner with little experience in surveying may be trusted to 

 execute, consists of a " Nativ," in which around plank is screwed, and serves 

 as a leaf. On the edge of this leaf are put 4 brass plates, with a deviation 



