708 SEC. 14. METEOEOLOGY. 



smaller cue a chain is passed, which is connected directly with the pressure 

 plate, and also with the recording- pencil. As the motion is direct, the spaces 

 moved through by the pencil and by the pressure plate are exactly equal to 

 another one and also to the primeter of the smaller curve. 



One great advantage of this apparatus consists in its close proximity to 

 the recording pencil, and in fact that the resistance is always the same, as 

 every part of the instrument except the pressure plate is under cover and 

 free from exposure to the weather. Another peculiarity of this instrument is 

 that the plate is furnished with a conical back, so as to diminish the error 

 arising from the formation of a partial vacuum behind it in strong winds. 



The direction of the wind is also continuously recorded by Beckley's 

 method, on the same paper as the pressure. 



288O. Whe well's Anemometer. Elliott Brothers. 



Consists of a delicate wheel with vanes and endless screw, working a series 

 of cog wheels, which communicate with an ordinary lead pencil, that registers 

 the force and direction of the wind on a vertical japanned cylinder. The 

 cylinder is enclosed in a wooden case to prevent it from being injured by 

 exposure to the weather. 



2882. Registering Aneroid Barometer, for showing at a 

 glance the various fluctuations that have taken place in the baro- 

 meter. Elliott Brothers. 



2883. Hewlett's Portable Anemograph, an instrument 

 which records the varying direction and force of the wind in 

 the form of a map. Elliott Brothers. 



2885. Self-recording Aneroid for Hall or Library ; a 

 graphic delineation of the change in pressure of the air for each 

 week can be seen at a glance. Francis Pastorelli. 



Fixed nearly in line, in a case, is an aneroid, an eight-day clock, and a re- 

 volving cylinder that occupies the central position ; it is covered with metallic 

 paper ruled for the days of one week, with the barometric scale in inches and 

 tenths ; upon this is marked every hour the pressure of the atmosphere ; the 

 markings have the appearance of a curved line, and the rise and fall of the 

 barometer is seen at a glance for every hour of each day for one week, when 

 a new paper has to be placed on the cylinder. The index hand on the dial 

 of the aneroid indicates the pressure of the air at the time of observation. 

 Having already described the construction of the aneroid, it is only necessarj- 

 to explain the method by which it is made self-registering. Connected with 

 the lever that carries the chain round the arbor is a long watch chain that 

 passes through the top of the aneroid over a pulley ; it terminates with a 

 metallic point, which is kept in working position by means of a vertical bar ; 

 this is capable of revolving upon its points. Behind the metallic point or 

 pencil is the vertical revolving cylinder covered with the metallic paper ; this 

 is moved by the clock, which also presses the pencil point down upon the 

 paper, and leaves a mark at each hour. 



2887. A. Von Oettingen's " Self-recording Wind Com- 

 ponents Integrator." Constructed by P. Schultze. 



Dr. Arthur Von Oettingen, Professor at the Imperial 

 University r , Dorpat (Riissia). 



