Thursday, April 3, 2008

from Report of the Annual Meeting of the British Association for the Advancement of Science, 1853

(page 235)

I have the honor to transmit an account of a singular phenomenon witnessed by myself and my family on the morning of the 4th of September, 1850.

I was then residing at the Vicarage, South Mimms, Middlesex, in a situation peculiarly favourable for astronomical observation.

I had been engaged for several consecutive days in observing the planet Mercury during his approach to the sun; partly to test the accuracy of my power of observation by the calculations of the Nautical Almanack, but chiefly to remark how nearly I could trace the planet in his course to the sun, before he should be wholly lost in his rays.

For this purpose I used the most careful adjustments my instrument was capable of, and continued my observations without noticing anything peculiar.

When, however, on the morning of the 4th of September I was preparing my equatoreal before it was fixed on the planet, I observed, passing through the field of view, in a continuous stream, a great number of luminous bodies; and I cannot more correctly describe the whole appearance, than by employing the same language which I used when I communicated the circumstance to the Royal Astronomical Society, in the Monthly Notices of Dec. 13, 1850, and Dec. 12th, 1851.

When I first saw them I was filled with surprise, and endeavoured to account for the strange appearance by supposing that they were bodies floating in the atmosphere, such as the seeds of plants, as we are accustomed to witness them in the open country about this season; but nothing was visible to the naked eye.

The sky was perfectly cloudless; and so serene was the atmosphere, that there was not a breath of wind through the day, even so much as to cause any perceptible tremor of the instrument; and I subjected the luminous bodies to examination by all the eye-pieces and coloured glasses that were needful; but they bore every such examination just as the planets Mercury and Venus did, both of which were frequently looked at by me, for the purpose of comparison, during the day; so that it was impossible I could resist the conclusion (much as I was early disposed to hesitate) that they were real celestial bodies moving in an orbit of their own, and far removed beyond the limits of our atmosphere.

They continued passing, often in inconceivable numbers, from half past 9 A.M., when I first saw them, almost without intermission, till about half past 3 P.M., when they became fewer, passed at longer intervals, and then finally ceased.

The bodies were all perfectly round, with about the brightness of Venus, as seen in the same field of view with them; and their light was white, or with a slight tinge of blue; and they appeared self-luminous, as though they did not cross the sun's disc; yet when seen near him they did not change their shape, or diminish in brightness.

They passed with different velocities, some slowly, and others with great rapidity; and they were very various in size, some having a diameter, as nearly as I could estimate, about 2”, while others were approaching 20”.

I tried various powers upon them, and used both direct and diagonal eyepieces; but with every one I employed they showed the same appearance, being as sharply defined as the planet Jupiter, without haze or spot, or inequality of brightness.

I naturally anticipated some such appearance at night, but after half past 3 I saw nothing peculiar, though I waited till 11 P.M.; but have since been informed that at 5 past 11 (it is believed on the same night) a meteor of amazing brilliance and size, and passing in the same direction and about the same altitude, was observed by Mr. Bailan of Wrotham Park, in the immediate neighbourhood of South Mimms.

I repeated my observations the following morning, and then saw one such single body pass in the same direction as those of the preceding day.

They occupied a tolerably well-defined zone of about 18° in breadth; and, though with some exceptions, their direction was due east and west. Their motion was perfectly uniform, so far as I was able to follow them with the instrument at liberty; and they were observed continuously by myself and members of my family, accustomed to the use of instruments, both by day and night.

The telescope I employed on this occasion is one of 3 1/2 feet focal length, and 2 3/4 inches aperture, by Mr. Dollond, of faultless performance and mounted equatoreally by Mr. Jones of Charing Cross, the circles divided by Mr. Rothwell of London, and reading off to 5".

I understand that a similar phenomenon has been witnessed by Mr. Cooper of Markree Castle, County of Sligo, though I have not communicated with that gentleman on the subject; but I take the opportunity of subjoining a portion of the contents of a letter to me from Charles B. Chalmers, Esq., F.R.A.S., now residing at Jugon, CĂ´tes du Nord, France.

He thus writes: “About the latter end of the year 1849, I witnessed a phenomenon similar to that which you saw in September 1850, in every respect, excepting that I thought some of the bodies were elongated, though certainly the majority were globular; and their brightness appeared to me about equal to that of Venus, as seen at the same time.

“I was then residing at Weston-Super-Mare, in Somersetshire; and the instrument with which I saw them was a 5-feet telescope, equatoreally mounted, in a fixed observatory.

“I was engaged similarly to yourself in observing the planet Mercury; about half past 10 A.M. I was at first inclined to believe it must be the seed of some plants of the thistle nature floating in the air, but from my position that could not have been the case.

“The wind on the day I observed the phenomenon was very slight; but such as it was it came from the sea. The bodies all appeared sharply defined, no feathery appearances that I could detect; and I did not observe any difference in their brightness during the time I observed them.”

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