Xo. 52 785. 



Barometers. 



373 



52 778. 

 1 :8. 



52779. 

 1: 10. 



52782. 

 1: 9. 



52 783. 

 1: 9. 



52785. 



1: 10. 



52.77. Syphon Barometer, after Brunn, Figure, can be used for accurate readings with s. d. 

 the cathetometer (Fr. phys. Techn. I, 2, Fig. 2552) 1.14.0 



The upper part of the tube is exhausted with the vacuum pump, the cock being then closed 

 and the apparatus tilted until the mercury has ascended into the upper vessel. When the instrument 

 is again placed upright the mercury divides and an absolute vacuum is formed in the main tube. If 

 air should collect in this later it can be shifted into the upper vessel quite easily by tilting. 



.")!.'. 777. Syphon Barometer with Glass Verniers and graduations on glass, Figure, the 



graduations being insensitive to the action of moisture 10. 0. 



52,778. Syphon Barometer with sliding wood rule, Figure, on black, polished board, with 



ebonite seal and two sighting vanes 1. 12. 



5.!. 779. - - idem, in case, portable, Figure, for measurements in mines, etc.; on black, 

 polished board, with adjustable wood rule, ebonite seal, sight-vanes and with thermo- 

 meter with Centigrade graduation 2. 6. 



52,780. Syphon Barometer, with sliding metal rule, otherwise as No. 52,778 2. 0. 



.")!', 78 1. Syphon Barometer, with etched graduations on the limbs, with 2 adjustable sight 



vanes 1. 10. 



52,782. Station Barometer, Figure, Eule adjustable by rack and pinion, verniers read 



with magnifying glasses 8. 0. 



52.7tf.'i. Syphon Barometer, after Krajevitch, Figure, with adjustable metal scale, with 

 rackwork and vernier, with cock on the short limb, plummet and thermometer graduated 



in Vs C., in case | 5. 0. 



Air bubbles can easily be forced into the extension of the long limb by tilting. 



52.784. - - idem, simpler, scale adjustment without rack 4. 0. 



52.785. Syphon Barometer, with adjustable Barometer Tube, Figure, with metal scale, 

 vernier and thermometer, the scales being silvered 3.10.0 



Cl. 861, 3344, 862, 5439, 5393. 



