No. III.

Description of a singular Phenomenon seen at Baton Rouge, by William Dunbar, Esq. communicated by Thomas Jefferson, President A. P. S.

NATCHEZ, June 30th, 1800.

Read 16th January 1801.

A PHENOMENON was seen to pass Baton Rouge on the night of the 5th April 1800, of which the following is the best description I have been able to obtain.

It was first seen in the South West, and moved so rapidly, passing over the heads of the spectators, as to disappear in the North East in about a quarter of a minute.

It appeared to be of the size of a large house, 70 or 80 feet long and of a form nearly resembling Fig. 5. in Plate, Iv.

It appeared to be about 200 yards above the surface of the earth, wholly luminous, but not emitting sparks; of a colour resembling the sun near the horizon in a cold frosty evening, which may be called a crimson red. When passing right over the heads of the spectators, the light on the surface of the earth, was little short of the effect of sun-beams, though at the same time, looking another way, the stars were visible, which appears to be a confirmation of the opinion formed of its moderate elevation. In passing, a considerable degree of heat was felt but no electric sensation. Immediately after it disappeared in the North East, a violent rushing noise was heard, as if the phenomenon was bearing down the forest before it, and in a few seconds a tremendous crash was heard similar to that of the largest piece of ordnance, causing a very sensible earthquake.

I have been informed, that search has been made in the place where the burning body fell, and that a considerable portion of the surface of the earth was found broken up, and every vegetable body burned or greatly scorched. I have not yet received answers to a number of queries I have sent on, which may perhaps bring to light more particulars.

F

NOTE. The above communication was accompanied by an account of the first invention of the Telegraphe extracted from the works of Dr. Hook.

Mr. Dunbar was induced to forward this extract to the Society, as he supposed it had been less noticed than it deserved to be. But it was deemed unnecessary to print the Paper, as it may be seen in the works above mentioned, and is referred to by Dr. Birch in his history of the Royal Society. Vol. 4th, page 299.

No. IV.

A short and easy rule for finding the equation for the change of the sun's declination when equal altitudes are used to regulate a clock or other time keeper. Communicated by Andrew Ellicott Esq.

FOR THE FIRST PART.

Read January 16th, 1801.

FIND the Sun's longitude, declination, and the change of declination for 24h at the time of the observation, likewise find the proportional part of the change of declination for the half interval between the forenoon and afternoon observations, then take the proportional logarithm answering to the change of declination for the half interval, (increasing the index by 10,) from which take the log. cosecant of the horary angle; to the remainder add the log. cotangent of the latitude of the place of observation, and take out the minute and second from the P. Ls. answering to the sum (10 being deducted from the index) which converted into time will give the first part of the correction and will be deductive in North latitudes, when the sun's longitude is 0, 1, 2, 9, 10, or 11, signs, and additive in the others; but the contrary in South latitudes.

FOR THE SECOND PART.

TO the P. L. of the change of the sun's declination during the half interval, add the log. cotangent of the sun's declination, from that sum deduct the log. cotangent of the horay angle.Take out the minute and second from P. Ls. answering to the remainder, which turned into time will give the second part of the correction; this is common to all latitudes, and will be additive when the sun's longitude is 0, 1, 2, 6, 7, or 8, signs, and deductive in the others.

1

EXAMPLE.

Suppose the following equal altitudes were taken in latitude 39°.56'. N. when the sun's longitude was 43. 15°.

The sun's declination answering to 4s 15° of his longitude is nearly 16o 21', and the change of declination at the same time about 16′ 55′′ in 24 hours, or 2′ 28′′ during the half interval.

THEN BY THE RULE.

Change of declination during

half interval 2′ 28′′ P. L.

11. 8631.

Horary angle 52° 30 log. cosec.-10. 1005

Latitude

1. 7626

39o 56' log. cotan. +10. 0772

P. L. 1. 8398=2′ 36"-10" 24"in

time, being the first part of the equation, and additive by the

rule.

FOR THE SECOND PART.

Change of declination during the

half interval 2′ 28′′ P. L.

1. 8631

Sun's declination 16° 21′ log cotan.+10. 5326

12. 3957

Horary angle 52′ 30′ log. cotan.-9.8850

P. L.-2.5107=0′ 33′′ 2′′ 12′′in

time, being the second part of the equation, and deductive by the rule.

Account of an extraordinary flight of meteors (commonly called shooting of stars) communicated by Andrew Ellicot, Esq. as extracted from his Journal in a voyage from New-Orleans to Philadelphia.

Read 16th January, 1801

“NOVEMBER 12th 1799, about three o'clock, A. M. I

was called up to see the shooting of the stars (as it is commonly called.) The phenomenon was grand and awful, the whole heavens appeared as if illuminated with sky-rockets, which disappeared only by the light of the sun after day break. The meteors, which at any one instant of time appeared as nume

rous as the stars, flew in all possible directions, except from the earth, toward which they all inclined more or less; and some of them descended perpendicularly over the vessel we were in, so that I was in constant expectation of their falling among us. My thermometer which had been at 86° of Farenheits scale for four days, fell to 56° about 4 o'clock A. M. and nearly at the same time the wind shifted from the South to the N. W. from whence it blew with great violence for three days without intermission. We were in latitude 25° N. and S. E. from Kay Largo, near the edge of the Gulph Stream."

I have since been informed that the above phenomenon extended over a large portion of the West India islands and as far North as Mary's in latitude 30° 42' where it appeared as brilliant as with us off Cape Florida.

No. VI.

Improved method of projecting and measuring plane Angles by Mr. Robert Patterson communicated by Mr. Andrew Ellicott.

SIR,

Read 6th March, 1801.

THE laying down, and measuring of plane angles, constitute so great a part of practical geometry, that any attempt to render this operation more easy and acurate than by the line of chords, or any other method now in common use, will not, I presume, be deemed altogether unimportant.

The lines of chords on our common scales are in general very inaccurately divided, and even if we suppose the divisions ever so exact it will still be impracticable to take off the measure of an angle to greater accuracy then a half or third of a degree at most; as it is impossible to apply either the nonius or diagonal method of subdivision to a line of unequal parts.

But in the method that I am about to propose a line of equal parts only is used, and therefore the divisions and subdivisions may, by either of the above modes, be made as minute and accurate as can be desired.