276 Mr. R. Hoskino- on the 



e 



perfectly similar in size and shape, and so the two marks on 

 either limb were placed symmetrically with regard to the 

 bulb between them, and, when the capillary tube was hori- 

 zontal, and limbs vertical, the two upper marks were in the 

 same horizontal plane, and likewise the two lower ones. 



The volume of liquid employed in the experiments is that 

 which the glischrometer holds when the one meniscus is level 

 with the upper mark in the one limb, and the other meniscus 

 coincides with the lower mark in the other limb. The 

 volume which flows through the capillary, however, is that 

 contained between the two marks on the same limb, diminished 

 by the small quantity which adheres to the sides of the bulb. 



The pressure is that due to a reservoir of compressed air, 

 which can be connected to either limb at pleasure, and is 

 measured by an open water-manometer, 



The time of flow is measured by a stop-watch, and the 

 temperature of the liquid is that of the bath surrounding it, 

 and is indicated by thermometers graduated to tenths. 



Measurement of the Constants of the Glischrometer. 



These constants i^re the semi-axes of the capillary, the 

 working length of the capillary, and the working volume of 

 the bulbs, where the working length of the capillary means 

 the measured length together with the Couette correction for 

 the open ends, and the working volume means the quantity 

 of liquid which flows through the capillary in an experiment. 

 These constants are determined before the portions of the 

 glischrometer are united together. 



The capillary tube was selected and cut from a much 

 longer piece which had been previously calibrated with 

 extreme care, and of which the mean diameter had been 

 obtained by weighing the mercury which had occupied known 

 lengths in the tube. The mean diameter of the selected 

 portion was deduced. The bore was slightly elliptical, and 

 the ratio of the axes was observed directly under a micro- 

 scope. From these two series of measurements, the values of 

 the semi-axes were obtained. The length of the capillary 

 was measured directly, the ends having been previously ground 

 perpendicular to the length of the bore. 



To obtain the working volume of the bulbs, a suitable 

 capillary tube was attached to the lower extremity of the limb, 

 and the limb filled with water. The pressure was then applied 

 above, and the liquid was driven through at about the same 

 rate as it would be in the ordinary experiments. The dis- 

 charge from the instant when the meniscus passed the upper 





