Mr King on a Nezv Self-registering Thermometer. It 5 



section of part of the tube B, and the bulb H, on a larger scale, 

 over which point C is joined a bulb H, for the sake of uni- 

 formity, equal as near as possible in form and capacity to 

 the other bulb of the instrument. The point C is immersed 

 among a little mercury contained by the bulb H, which it oc- 

 cupies up to the line D. The other leg and bulb A and G, as 

 already mentioned, are supposed to be a properly adjusted 

 thermometer filled with mercury. All the other space of the 

 tube, which forms the legs A and B, is filled with very pure 

 and colourless alcohol ; and part of the remaining space in the 

 bulb H is also filled with alcohol up to the dotted line E. The 

 still remaining space in the bulb H is allowed to be filled with 

 atmospheric air. The tube must be of as equal calibre as possi- 

 ble. A scale divided into parts equal to the degrees of the ther- 

 mometer or leg A, is attached to the leg B, reckoning from 

 the point C upwards, allowing the first division or two to be 

 a little larger, in proportion as the tube is contracted in its di- 

 mensions at the extremity. If this instrument is hung up, and 

 so arranged that the leg B is filled only with alcohol, by an 

 increase of temperature, the mercury in the leg A will rise ac- 

 cordingly, and a proportional quantity of the alcohol in the tube 

 will be pressed out of it at the point C ; and on account of the 

 superior specific gravity of the little mercury among which it 

 is immersed, that part of the alcohol which may thus be pressed 

 out of the tube at C will rise through and rest on the upper 

 surface of the mercury in the bulb H. Should the temperature 

 again be reduced, the mercury in the leg A will of course suf- 

 fer a corresponding depression in the tube, and a quantity of 

 mercury which is contained in the bulb H will consequently 

 be pressed by the elastic force of the contained air, up to 

 the leg B ; and in proportion as the leg B is filled with mer- 

 cury, say up ten divisions of the annexed scale, an equal num- 

 ber of degrees are to be added to the degrees of temperature 

 at the time of observation, which will give the maximum tem- 

 perature since the last observation or adjustment of the instru- 

 ment. 



. To again adjust the thermometer, apply the warm hand to 

 the bulb G, to cause the mercury in the leg A to rise, till the 

 whole of the mercury be again expelled out of the leg B; then 



