II. BAROMETERS. 677 



SET OF INSTRUMENTS made on the KEW PATTERN, by P. ADIE, 

 for the PHYSICAL OBSERVATORY, at POTSDAM. 



27891. Magnetometer. Dr. H. W. Vogel. 



2789m. Declination Magnetometer. Dr. H. W. Vogel. 



2789n. Vertical Force Magnetometer. 



Dr. H. W. Vogel. 



2789o. Automatic recording Apparatus. 



Dr. H. W. Vogel. 



II. BAROMETERS. 

 a. MERCURIAL. 



2790. Large Standard Barometer, -^~ f tube, with English 

 and metrical scales, glass plunger cistern, and pipette in tube for 

 preservation of vacuum. Patrick Adie. 



2791. Medium Standard Barometer, T %" tube, with glass 

 plunger cistern, and pipette in tube for preservation of vacuum. 

 As used in Government meteorological observations. 



Patrick Adie. 



2792. Small Standard Barometer, with glass plunger 

 cistern, and pipette in tube for preservation of vacuum. Medical 

 Department, War Office pattern. Patrick Adie. 



2793. Large Standard Barometer, with single readings. 

 Kew Observatory verification, and pipette in tube for preservation 

 of vacuum. Kew pattern. Patrick Adie. 



2794. Medium Standard Barometer, with single readings, 

 KCAV Observatory verification, and pipette in tube for preservation 

 of vacuum. Kew pattern. Patrick Adie. 



2795. Mountain Barometer, Fortin's, on tripod, with pipette 

 in tube for preservation of vacuum. Patrick Adie. 



2796. Gay-Lussac's Portable Barometer, with pipette in 

 tube for preservation of vacuum. Patrick Adie. 



2796a. Standard Barometer with Electrical Adjust- 

 ment. Negretti and Zambra. 



This is a tube clipping into a glass cistern of mercury, fitted with a vertical 

 adjustment screw. Through the top of the tube a platina wire is passed and 

 hermetically sealed. The cistern has a metallic connexion, so that by means 

 of copper wires (in the frame) a galvanic circuit is established ; another con- 

 nexion also exists by a metallic point dipping into the cistern. The circuit, 



