41 
the shorter limb ; as the inclination continued, the mercury 
and water began to change places, and the water passed up 
round the bend into the longer limb ; when 5 or 6 inches of 
water had passed in, the tube was erected and turned over 
the other way, so that the closed end was lowest, the water 
and the bubble of air running up and passing out. The 
tube was then further inclined until nearly vertical, the 
closed end down, and the tube was left in this position for 
24 hours. 
This, it will be noticed, was the process by which, after 
the first trial, had proved almost invariably successful with 
the former tube, and the only circumstances likely to cause 
any difference in the new and old tube were the compara- 
tively short time the water and mercury had been together, 
and in the new tube, and the greater length, 90 inches, as 
against 60 with the old tube. As regarded this latter differ- 
ence, it would not effect a partial erection of the tube, so 
that if the time was not an element of importance, it was to 
be expected that at all events the mercury would sustain 
itself until the closed end had reached a r position 60 inches 
above the bend. 
On examining the tube, however, after it had been stand- 
ing 24 hours, it presented a very different appearance from 
that usually presented by the old tube ; instead of a polished 
column of mercury it was frosted with water between itself 
and the glass ; it was clear that the upward draining of the - 
water had been very imperfect, a great deal remaining 
adhering to the glass. 
On slowly erecting the tube the mercury showed no 
symptom of suspension, leaving the closed end quietly as 
erection proceeded. 
The whole process of passing the water up the tube was 
again repeated with the same result for three days. 
The frosted appearance, however, gradually diminished 
and on the fourth day a partial suspension was obtained. 
The mercury remained up until the tube was nearly erect. 
