Eptiome of the electro-meteorological and magnetic observations, experiments, etc. made at the Kew Observatory / [Sir Francis Ronalds].

  • Francis Ronalds
Date:
1848
Catalogue details

Licence: Public Domain Mark

Credit: Eptiome of the electro-meteorological and magnetic observations, experiments, etc. made at the Kew Observatory / [Sir Francis Ronalds]. Source: Wellcome Collection.

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    conductor*on the pagoda, and it was presented at the Office of Woods, &c. by Sir William Hooker, but the subject was not further prosecuted. This 2nd volume of observations, &c. with descriptions (and drawings,) of instruments and experiments, was completed and carried to the Cam¬ bridge meeting on June 19, 1845. 3rd. Vol. The collection of instruments for ordinary observations recorded in this Volume, remained unaltered, excepting that the gold-leaf electroscope was now placed under a glass bell, with some chloride of calcium, in order to preserve it in a state perfectly dry, and fit for immediate use. The journal begins on the 19th of June, 1845, and ends September 10, 1846; 14 observations per diem were made, as usual, of the electro¬ meters. In July, 1845, my experiments (in pursuance of my previous proposals in 1840, 1841, and 1844,) on the photographic registration of all meteoro¬ logical and terrestro-magnetical instruments, began at this Observatory. The first attempts, which should be esteemed quite successful, were upon an artificially charged Voltaic electrometer, on August 2nd, 1845, {vide “ Kew Photographs;)” upon a thermometer, on the 5th of August, 1845 ; and upon a barometer on the 15th of August, 1845. Previously to these, I had made some rough experiments, and had received some assistance in the chemicalities from Mr. Collen. On the 24th of September, 1845,1 obtained the first good specimen of registered atmospheric electricity; and on the 25th, and frequently after¬ wards, the apparatus enabled me to observe the curious fact, that the elec¬ tric tension increased with the light of the sun, under certain circum¬ stances, but that such increased tension did not continue. In the beginning of November, 1845, these experiments on either the thermometer, barometer, or electrometer, having been repeated almost daily since the 2nd of August, and the specimens having displayed suffi¬ cient exactitude, I ventured to recommend the use of the method as re¬ garded the electrometer particularly, in preference to that of the resinous- plate electrograph at Greenwich: for the Astronomer Royal had said in his excellent “ Report ” of June, 1845, that “if an efficient self-registering appa¬ ratus could be arranged, preserving its records in a permanent form, be should propose to mount an electric apparatus, nearly similar to that at Kew, on the top of the octagon room.” On December (6th) 1845,1 first applied a kind of Distinguishing electro¬ meter to the photographic microscope (or camera), in pursuance of a hint from the Astronomer Royal in reference to the dry pile distinguishing apparatus (of Bohnenburger) of gold leaf. In December, 1845,1 began to work upon the application of the system to the Declination magnet, and made drawings, patterns, &c. in January, but had not actually tried it, when, on the 9th of February, 1846, Mr. Brooke came to Kew (meeting Colonel Sabine and other gentlemen there) and I shewed him many very good specimens of my process on the elec¬ trometer, &c. and fully explained to him all my proceedings in procuring them. He shewed but two or three specimens of his process on the magnet, wherein the line was confused and scarcely distinguishable. Colonel Sabine (and I believe every body else) gave to my method the preference greatly. In February, 1846, the Astronomer Royal lent me a Greenwich magnet. In March, 1846, a little alteration was made in the (former) transit-room,