278 Progress in Science. [April, | 
Negretti and Zambra’s patent maximum thermometer, which cuts off, in the 
moment of turning, the mercury in the column from that of the bulb in 
the tube, thereby ensuring that none but the mercury in the tube can be 
transferred into the indicating column; E is an enlargement made in the 
bend, so as to enable the mercury to pass quickly from one tube to another 
in revolving; and F is the indicating tube, or thermometer proper. In its t 
action, as soon as the thermometer is put in motion, and immediately the 
tube has acquired a slightly oblique position, the mercury breaks off at 
the point p, runs into the curved and enlarged portion E, and eventually 
falls into the tube F, when this tube resumes its original perpendicular 
position. The contrivance for turning the thermometer over may be 
described as a short length of wood or metal having attached to it a small : 
rudder or fan: this fan is placed on a pivot in connection with a second; on 
the centre of this is fixed the thermometer. The fan or rudder points up- 
wards in its descent through the water, and necessarily reverses its position 
in ascending. This simple motion, or half-turn of the rudder, gives a whole — 
turn to the thermometer, and has been found very effective. Various other — 
methods may be used for turning the thermometer, such as a simple pulley — 
with a weight which might be released on touching the bottom, ora small — 
vertical propeller which would revolve in passing through the water. Messrs, 
Negretti and Zambra have also adopted a very simple and inexpensive clock- — 
work to their thermometer, and by these means an observer may have a record 
of the exact temperature at any hour of the day or night. We need hardly © 
say of what utility the instrument will prove to meteorologists, and even — 
manufacturers, to whom an exact record of temperature is of importance. { 
Hitherto we have had no simple and inexpensive instrument adapted for this 
purpose: the thermograph in use at most observatories is an elaborate and 
expensive apparatus, which, in connection with photography, will record on 
paper the temperature during day or night; it necessitates the use of gas, or 
any artificial light, and of course is only available to persons who can have a 
building specially adapted for it. 
ELEctTrRIcITY.—At a recent meeting of the Manchester Literary and 
Philosophical Society Professor Osborne Reynolds, M.A., read a paper “ On the 
Bursting of Trees and Objects struck by Lightning.” In a previous paper on 
this subject he stated that the tube which was burst by a discharge from a 
jar would probably withstand an internal pressure from 2 to 5 tons on the 
square inch; and he made use of the expression the tube might be fired like 
a gun without bursting. These statements were based on the calculated 
strength of the tube, and with a view to show that there was no mistake, the 
author tried it in the following manner:—He made three guns of the same 
tube. No. 1, which was 6 inches long, had its end stopped with a brass plug 
containing the fuze hole. Nos. 2 and 3 were 6 inches long, and had their 
breeches drawn down so as only to leave a fuze hole. These tubes were 
loaded with gunpowder and shotted with slugs of wire which fitted them, 
and which were all 3? inch long. No. 1 was first fired with } inch of powder, 
the shot penetrated } inch into a deal board, and the gun was uninjured. 
No 2. was then fired with 1} inches of powder, and the shot went through the 
1 inch deal board and } inch into some mahogany behind, thus penetratin 
altogether 1} inches; the tube, however, was burst to fragments. Some at 
these were recovered, and although they were small they did not show cracks” 
and signs of crushing like those from the electrical fracture. No. 3 was then 
fired with ? inch of powder, and the shot penetrated } inch into the deal 
board. It was again fired with 1 inch of powder, and the shot penetrated 
1 inch into the deal. Again it was a third time fired with 1} inches of powder, 
when it burst, and the shot only just dented the wood. These experiments: 
seem to prove conclusively the great strength of the tube and the enormous 
bursting force of the electrical discharge. 
At the first meeting of the Physical Society of London the Chairman (Dr. 
Gladstone, F.R.S.) gave a brief description of the objects and organisation of 
the Society, and announced that ninety-nine gentlemen had already expressed 
their desire to join the Society as original members. 
