834 



state has returned in L. The bifilarly wound wire now, placed on 

 the top of the measuring tube (cf. p. 83ij supplies the want of such 

 a thermoscope. This resistance is led outside by the third and fourth 

 insulated wires of the piece M, and brought in connection with a 

 Wheatstone bridge. The galvanometer of this combination indicates 

 if the stationary state has set in. 



Separate experiments made at atmospheric pressure, so that a 

 resistance thermometer can be put in the space inside L, and moved 

 to and fro, have proved that when the stationary state in L has 

 set in, the same temperature prevails exerywhere in L ; at least for 

 the temperature at the top and the bottom of L (making use of the 

 thermostat which is to be described presently) no difference of 0°,01 

 could be demonstrated. 



It also appeared that the temperature measured within L and in 

 the thermostat that surrounds L, agreed to within the same amount. 

 This was, however, not the case until not only the whole piece L, 

 but also the closing pieces M, projecting at the top and at the bottom, 

 and a part of the adjoining tubes had been enclosed in the thermostat. 

 In a smaller apparatus constructed first, in which the extremities of 

 L projected outside the thermostat, differences of the order of 

 magnitude of i° could be demonstrated inside L. 



The arrangement of the thermostat can be sketched in a few 

 words. Round L on a steel cable If, which runs over pulleys 

 fastened to the ceiling, hangs a plate-iron cylindre jacket Z balanced 

 by counterpoises ; it can be slid up and down a few d. m. On the 

 tube 0, which leads from the cock H to M is placed oiltight by 

 by means of a packing box an iron circular plate A', whose section 

 is a little larger than that of the cylindre. At its bottom the cylindre 

 carries a flange, which can be fastened by bolts and nuts on the 

 plate, when the closing piece M and the tube have been sufficiently 

 screwed tight by means of the nut K belonging to it. A leather 

 packing between flange and plate renders this closure oiltight. The 

 cylindre jacket remains open at the top. An oil pump worked by 

 the repeatedly mentioned transmission shaft then fills the whole 

 thermostat with oil from the large iron stoi-e reservoir. By means 

 of a stop-cock fastened in the plate .Y (not dra\vn) and a hard lead 

 tubing connected with it, the oil can again be collected in this store 

 reservoir. In a fixed position attached to the cylindre jacket, and 

 therefore moving up and down with it is a stirrer, which when it 

 has been put in its place can again be set going by the transmission 

 shaft. Inside the cylindre a large toluol thermoregulator is suspended, 

 which is in connection with a gas flame which plays against the 



