TRANSACTIONS OF THE SECTIONS. 17 
It is probable, also, that the temperature of the steam in the manometer was, from 
exposure to the air, less than that of the steam in the boiler, so that the small ther- 
mometer may be expected to give the temperature too high rather than too low. 
An Account of an Atmospheric Recorder. By G. Dotionp, F.R.S. 
It having appeared to be desirable at the last meeting of the British Association 
that a correct self-registering apparatus should be constructed, by which the various 
changes of the atmosphere should be recorded upon paper, in such manner that they 
might be referred to at a future period, I have the pleasure to describe an apparatus 
which records the indications of the following eight instruments, viz. the barometer, 
the thermometer, the hygrometer, the electrometer, the pluviometer, the evaporator, 
the force-board, and the anemometer, in relation to time. I have found it answer the 
purpose for which it was intended, in every way satisfactorily, 1st. The barometer 
registers the change which takes place in the weight of the atmosphere at every half- 
hour, and the line may be traced from one point to the next without any difficulty. 
2nd. The thermometer registers the various changes from cold in the night or morn- 
ing, to the greatest heat in the afternoon, continuously. 3rd. The hygrometer is 
adjusted to show the changes from dryness to extreme saturation of moisture to every 
hundredth of the scale, and is extremely steady in action, 4th. The electrometer is 
acted upon by a conductor, and registers each flash of lightning which comes within 
the range of the conductor, 5th. The pluviometer registers the drops of rain which 
fall upon the surface of the receiver, and shows the continuation of the falling quan- 
tity until an inch is received; this is then discharged and the process recommences 
for another inch, and so on continually. 6th. The evaporator is so constructed as to 
retain a quantity of water with the surface exposed, and so guarded that rain cannot 
enter into the vessel. The surface gradually evaporates, as shown by a diagonal line 
upon the paper until an inch is evaporated, when a discharge takes place and another 
line commences. 7th, The force or power of the wind acts upon a board one foot 
square, whose movement is registered in pounds and ounces avoirdupois, from one 
ounce to thirty pounds. 8th. The direction of the wind is shown in circles, which 
immediately upon inspection show the direction of the course or change which has 
taken place, for instance, if it has passed through the south or the north, from east to 
west, and the point from which it started and that to which it returned. All these 
eight varieties have their scales about half an inch from the marking-points, and can 
be very easily read or referred to. There are markers on each edge of the paper for 
time, the paper being carried forward by a clock. 
Mr. Dollond gave an account of the storm, as shown by this instrument, at Cam- 
berwell on the 1st day of August 1846, during his absence :— 
The barometer changed from............... 30°03 inches to 29°82 inches, 
The thermometer FFOM.......000002s+- 69° to 98° 
during the day, or twenty-four hours. 
The hygrometer ranged from 39° to 80° of moisture. 
At two o'clock the electrometer was affected by the lightning, and registered fifteen 
discharges or flashes in one hour. 
At 35 23! the rain commenced falling, and in two minutes the pluviometer dis- 
charged an inch, which had previously stood at 11°90 for several days. At 4° 3! 
"another inch was registered, and at 55 25!’ a third inch was marked upon the regis- 
tering paper ; and so tremendous was the fall of rain and hail, that at 5% 35! a fourth 
inch was marked upon the paper, making on the whole 3°12 inches in 25 17’. 
The force of the wind was equal to one pound four ounces, and the direction 
changed from east to west, through the south at 3" 20'. 
On the Construction of a Self-registering Barometer, Thermometer, and 
Psychrometer. By C. Brooxe, MB. 
"Mr. Brooke remarked that he had been induced by the want of efficient means of 
automatic registration of the variation of meteorological instruments, and especially 
of magnetometers, which was so generally expressed at the last meeting of the British 
—«*1846. c 
