II. LENGTH. 67 



The slide which carries the tracing point moves without greasing between 

 six finely polished carnelian plates ; by this arrangement any errors, which 

 might be caused by clotted grease, will be rendered absolutely impossible. 



F. TIDE REGISTERS. 



327b. Patent Indicator, for tanks or reservoirs. 



John Nicholas. 



This gauge is similar to that last described, but the atmosphere giving 

 comparatively a constant pressure the stand pipe can be dispensed with. 

 The brass tube referred to in the previous description may be seen in the tank 

 attached. It is not necessary to pierce or employ a tank when attaching one 

 of these gauges, and the small pipes can be laid in the walls in a similar 

 manner to gas tubes. In some cases one tube is sufficient, the water column 

 being balanced by mercury in a metal tube at the back of the gauge. This 

 gauge is suitable for tanks upon the roofs of mansions or hotels, where engines 

 are used for pumping. 



255. Registering Water-mark, of new construction, which 

 records the curve of the water-level and its mean height. 



Lieutenant- General Baeyer, President of the Geodetic 

 Institute at Berlin. 



Invented by F. H. Reitz, civil engineer, of Hamburg. The apparatus 

 was made in the factory of Pape and Dennert. The clockwork is by 

 Knoblich. 



278a. Magneto-Electric Water Level Indicator. 



Siemens and Halskc, Berlin. 



A float which rises or falls with the level of the water in the reservoir or 

 tank communicates motion by a metallic chain to a magneto inductor, which^ 

 generating electric currents, works at any distance an indicator connected by 

 a cable or insulated wire. 



1695. Apparatus for making contact to show the height of 

 water with float, rod-chain, counterpoise, and water tube. 



C. # E. Fein, Stuttgart. 



This is self-acting, and registers at any distance the water-level in a 

 reservoir, &c. 



It consists of five parts : 



(1.) The float with chain and counter weight which when acted on by the 

 rise or fall of the water impart their motion to the contact arrange- 

 ment 



(2.) The contact arrangement which communicates the motion of the float 

 to the recording instrument by opening or closing the circuit. 



(3.) The recording instrument ; this shows the level of the water at all 

 times, the pointer being acted on by the motion to and fro of two 

 electro-magnets. 



(4.) The conducting wire. 



(5.) The battery. 



279. Three Gauges, in enamel cast iron, for registering the 

 height of a river or lake. De Dietrich and Co., Niederbronn. 



E 2 



