57G SEC. 14. METEOROLOGY. 



2826g. Standard Thermometer, in maroon case. 



L. Casella. 



2826h. f Maximum Thermometer. L. Casella. 



28261. < Minimum Thermometer, with forked bulb. 



L L. Casella. 



2326}. Thermometer, 2 in. long, set in wood and zinc, divided 

 into -i- , for investigations of terrestrial heat. 



Warmbrunn, Quilitz, 8? Co., Berlin. 



2826k. Two Thermometers. Maximum thermometers in 

 case. Will. Haak, Neuhaus, Thuringen. 



28261. Two Thermometers. Maximum on brass scale. 



Will, ffaak, Neuhaus, Thuringen. 



2826m. Continuous Self-registering Thermometer. 



W. Harrison Cripps, F.R.C.S. 



The object of the instrument is to obtain a continuous registration of heat. 

 The instrument is in two portions : 1st, the thermometer for indicating the 

 temperature ; 2ndly, the clock-work for registering the hours and minutes. 

 The thermometer consists of six coils of glass tubing wound concentrically 

 round an axis in such a manner as to form a spiral glass wheel 4 inches in 

 diameter. The last coil is moved slightly away from the others, so that it 

 shall form the circumference of a circle 5 inches in diameter. To each end 

 of the axis a fine needle-pointed-pivot is attached. These pivots rest on 

 minute depressions between two parallel metal uprights. By this arrange- 

 ment the glass wheel can rotate freely between the uprights. The spirit in 

 the thermometer fills the spiral portions of the tube, and also 3 or 4 inches of 

 the last coil (the one forming the circle). The spirit then comes into contact 

 with a column of mercury 4.inches in length. Beyond the mercury are a few 

 drops of spirit to moisten the glass. The remaining portion of the tube is 

 hermetically sealed, enclosing a small quantity of air. On the spirit expand- 

 ing with heat, the column of mercury is driven forwards. This immediately 

 alters the centre of gravity, and the wheel revolves in a direction contrary to 

 that of the moving mercury. When the spirit contracts on cooling the en- 

 closed air acting as an elastic spring keeps the mercury in contact with it, 

 and the wheel regains its original position. By this arrangement the two 

 forces, heat and gravity, acting in contrary directions, generate a steady 

 rotary of motion. 



The method by which this movement is made serviceable is by a grooved 

 wheel 2 inches in diameter fixed to one of the pivots, and therefore revolving 

 with the thermometer. Fixed to and passing over this wheel is a fine thread, 

 from which is suspended a pencil holder, moving up and down on a vertical 

 slide. The pencil will be raised or lowered according to the direction in 

 which the wheel is moving. The other portions of the clock-work are 

 arranged in a manner similar to that employed in the barograph. 



In the present instrument a cj'linder 4 inches, both in width and diameter, 

 is made to revolve once in seven days. Around this cylinder is placed a 

 paper, on which the days and hours are indicated by vertical lines. The 

 cylinder is so placed that the surface of the paper is -^th of an inch away from 

 the pencil point, moving at right angles to its surface. A small striker is 

 connected with the clock-work in such a manner that at every quarter of an 

 hour it gives the pencil a tap, striking its point against the paper. 



2326n. Fluctuation Thermometer. Prof .Balf our Stewart. 



