xl REPORT—1843. 
glass pillar only, and not, as usual, upon separate insulators which dissipate 
the electricity unequally. 
The instruments which are at present in action are,—lIst, two Volta’s 
straw electrometers, one degree of the second corresponding with five degrees 
of the first; 2nd, a Henly’s electrometer, one degree of the scale of which is 
equivalent to ten degrees of the least sensible of Volta’s electrometers; 3rd, 
a modification of Coulomb’s torsion electrometer, which, while it possesses the 
sensibility of the most delicate of Volta’s straw electrometers, has a range as 
great as the preceding three instruments; 4th, a dry pile electrometer; 5th, 
a discharging electrometer for measuring the lengths of sparks; 6th, an at- 
mospheric galyanometer with 2400 well-insulated coils, made by Gourjon of 
Paris; 7th, Mr, Ronalds’s modification of Landriani’s electrograph, an in- 
genious instrument which records, during the absence of an observer, the 
electrical states of the conductor, distinguishing the positive from the negative 
states, and to a certain degree the variations of intensity. Many other instru- 
ments are in progress from which new and useful results are expected, but 
which it would be at present premature to mention. 
Since the apparatus has been completed the conductor has remained con- 
stantly charged, unless purposely discharged, or during the momentary trans- 
itions from one electrical state to the other. The electric tensions vary in 
serene weather between 3° and 90°, and the diurnal changes are indicated 
with great precision. This report is accompanied by a sectional drawing of 
the Electrical Observatory, and by a register of observations commenced on 
July Ist, and continued regularly for six weeks. Observations made during 
the same time with the barometer, pluviometer, thermometer, psychrometer, 
Daniell’s and Saussure’s hygrometers, &c., are also annexed to the report. 
Report on the Electro-magnetic Meteorological Register. 
By Professor Wunatstons, F.R.S, 
Tue electro-magnetic meteorological register which I undertook to construct 
for the Observatory of the British Association is just completed. I will de- 
fer to a future occasion a full account of its mechanism, and of the various 
modifications I have devised to render it suitable for the different purposes 
required in meteorological investigations ; such an account will more properly 
accompany the record of the daily working of the instrument, which I hope to 
present at the next meeting of the Association. I will confine my present 
report to a concise description of the instrument in its present state, but be- 
fore proceeding to this I will briefly mention what it effects. 
It records the indications of the barometer, the thermometer and the psy- 
chrometer every half-hour during day and night, and prints the results, in 
duplicate, on a sheet of paper in figures. It requires no attention for a week, 
during which time it registers 1008 observations. Five minutes are sufficient 
to prepare the machine for another week’s work; that is, to wind up the 
clock, to furnish the cylinder with fresh sheets of paper, and to recharge the 
small voltaic element. The range of each instrument is divided into 150 
parts; that of the barometer comprises three inches, that of the thermometer 
includes all degrees of temperature between — 5° and + 95°, and the psy- 
chrometer has an equal range. 
The machine consists essentially of two distinct parts: the first is a regu- 
lator clock, to which are attached all the regularly recurring movements which 
require to be introduced ; the second is a train haying an independent main- 
taining power, which is brought into action at irregular periods of time by 
the contact of the plunging wires with the mercury of the instruments, as 
will be hereafter explained. 
