a Bar Level, shown in V\g. 29, is unsurpassed in convenience and 

 adaptability. It may be mounted in the case with the instrument 

 and serve other useful purposes. The Bar Level may be adjusted by 

 placing it on the planchette; bring bubble to center by tapping the 

 board, reverse bar level end-for-end and correct half errors in the 

 board and the adjusting screws of vial mount until the bubble remains 

 centered in both positions. 



The Declinatoire, or box compass, is indispensable, for the 

 reference line is usually the local magnetic meridian. It is generally 

 mounted on the base rule in preference to inserting it in the edge of 

 the planchette, but we are prepared to furnish it for this purpose, as 

 shown in the marginal cut Fig. 27, if so desired. It is provided with 

 one of our tubular compass needles w r ith sapphire mounting, as 

 enthusiastically approved by Government officials and many others 

 who have used them. The Declinatoire has no adjustment except 

 the clamping device and the balance of the needle, which must be, 

 adjusted by the user for different latitudes. To do this remove the 

 metal cover that envelopes the central portion of the box and, sliding 

 the glass window back, the needle becomes accessible. The mount- 

 ing and clamping device employed insures the needle against 

 dismounting when undamped. (See also page 140). 



The Micrometer Alidade 



No. 92 Telemetric Alidade with Interchangeable Oculars. 



-IS 



