(32) 
vided with loose glass covers; the whole is covered by a double 
layer of felt. 
In order to be able to properly mix the water in the heating 
bath and in the mixing bath the stirrers Q and F# have been made, 
each provided with six blades!). In order to prevent a general 
rotation of the water which would delay the perfect mixture, vertical 
baffle plates 7' have been fixed vertically to the inner wall of each 
vessel. At their upper ends the axes @ and Ff are provided with 
grooved dises U and V, connected by a string consisting of a spirally 
wound wire. The axis B also carries a disc W, connected by a 
similar string with the small disc X on the axis of the watermotor 
Y*). In order to prevent strain in the apparatus the axes are 
connected by strong iron bands Z; while the axis of the motor is 
supported by the tube a which also serves as oil-reservoir *). The 
water from the water supply streams through the motor to the 
overflow A. 
Stirring is also necessary in order to obtain an equal temperature 
in the observing bath. For this purpose two brass rings e, are con- 
nected by means of three glass rods, and moved by a chord f over 
a pully (see Plate Comm. NO. 50). In order to assist the mixing 
by convection the water is admitted at g and runs off above at 7. 
§ 3. The Xylene-thermo-regulator. The only important thing left 
was to construct a suitable regulator for the heating bath. The known 
regulators of Gouy*), DOLEZALEK, GUMLICH®) and others, which 
work electromagnetically, seemed less suitable, since there the regu- 
lating flame is repeatedly extinguished and with a view to the large 
quantity of heat required, this cannot but give rise to too great 
variations of temperature. I thought it therefore better to return to 
liquid regulators, as with these small gradual variations could be 
1) The plane of these blades is bent at an angle of 45° as shown in the figure 
for a pair of blades S; they are bent so that in rotating alternate blades move the 
water upwards and downwards. 
2) The motor consists of a box Y; at a distance of 4 of the circumference two 
parallel tubes 5 and c are fixed. Above these tubes a horizontal plate is fastened to 
the axis, provided with vertical blades at angles of 45° with the radius, so that they 
are placed crossly before ¢ and straight before 4. 
3) To facilitate taking the apparatus to pieces the axes Q and Z have been cut 
through; and the parts are fixed to the connecting tube by means of pins d. 
4) Gouy, Journ. de Phys, (8) 6, p. 479, 1897. 
5) Gumuicu, Ueber einen Thermoregulator fiir ein weites Temperaturgebiet. Zeitschr. 
für Instr. 1898, 
LS eee rl eer rrtrt—‘S 
