146 SEC. 0. MOLECULAR PHYSICS. 



673b. Multiplying Manometer, for measuring the force of 

 draught in chimneys, and stoves, as well as for the pressure of 

 gas. Dr. K. List, Hag en, Westphalia. 



This apparatus was first constructed by the exhibitor in 1862 for the 

 purpose of meeting the desire of several puddling furnace proprietors 

 resident at Hagen, who wished to be able to measure more accurately the 

 draught in their furnaces than was possible with the ordinary manometer, 

 consisting of a curved glass tube, as is mentioned in the description given in 

 the " Zeitschrift des Vereins deutscher Ingenieure," (Journal of the German 

 Society of Engineers) of 1863, vol. vii, p. 493. It consists essentially of 

 a long narrow horizontal and two wider vertical glass tubes, the latter of 

 which are filled to about half their size, and the first up to a long air-bubble, 

 with coloured petroleum. If a suction is effected on one of the vertical tubes, 

 the air-bubble contained in the horizontal tube must, in case the vertical tube 

 should have a diameter n times as large as the horizontal tube, travel a space 

 n 2 times as large as the liquid rises or falls, as the case may be, in the vertical 

 tube ; the sensibility therefore, can be increased at pleasure. The space which 



the index travels is -^ times as large as the difference in the respective heights 



of the liquid in the two vertical columns. 



The apparatus having been constructed for some years by the exhibitor 

 himself, the scale indicating in water-millimeters the difference of pressure 

 was prepared by him in the manner described in the Journal of the German 

 Society of Engineers mentioned heretofore. The apparatus has answered 

 well everywhere. It has been recommended for measuring the pressure of 

 gas by authorities such as Schiele in Frankfort-on-Maiue and Schilling at 

 Munich. 



673c. Level for Manometer. M. Breguet, Paris. 



673d. Control Manometer, with two-fold safety. 



C. D. Gabler, Hamburg. 



1. The advantage here consists in two independent manometers, acting 

 under quite similar conditions, being combined in one case, whereby not only 

 a greater guarantee of control is obtained, but by the close proximity of the 

 two scales the simultaneous reading of the divisions is facilitated. The 

 upright position of the tubes prevents the collection of impurities out of the 

 water, as the latter flows freely away after use. The instrument may be con- 

 nected by a simple screw arrangement with the boiler. 



673e. Control Manometer, with four-fold safety. 



C. D. Gdbler, Hamburg. 



This manometer, consisting of two manometers of the above construction, 

 combined one with the other, offers the greatest possible safety in controlling ; 

 because, if only two-fold safety be asked, the one pair of manometers can be 

 put out of action by closing the stopcock, and may thus be used as reserve or 

 control of the manometer thence used. The connexion with the boiler 

 nanche is performed by means of the accompanying two thumb nut-screws. 



673f. Control Manometer, showing the inner construction. 



C. D. Gabler, Hamburg. 



Shows the extremely simple construction of the inner mechanism of the 

 manometers described above. 



