140 
NALURE 
| Dec. 7, 1882 
appeared at only 8° altitude, and it is described as 6° under the 
moon, or 19° alt. ; and the passage from Woodbridge to Bristol 
could not occupy over two hours (at a mile a minute), as the 
whole difference of time is certainly only a minute or two. We 
must then seek for more consistent elements. 
From the York, Bedford, and Old Windsor observations, 
meteor was at about 170 miles elevation, allowing the first sta- 
tion half the weight of the second. Or, combining York and 
Bristol, which were more nearly simultaneous, it was at over 300 
miles elevation. Its visible passage of about 200 miles in length 
did not occupy two minutes, and was so brief as to be masked 
by the watch errors of observers ; it therefore moved more than 
100 miles a minute. Again, it was two minutes in view, by 
Greenwich ; and ir passed the meridian with at least twice its 
mean apparent velocity (as most observers mention its lingering in 
both east and west) ; tbis, with the least height of 170 miles, gives 
a minimum of fifteen miles per second for its velocity. Another 
proof of its height is, that though seen in Sweden, yet it appeared 
to form and pause at 10° alt., as seen at Bristol and Heworth, 
and did not come up from the horizon. 
Can it be supposed that an auroral ray would sweep over 10co 
miles from Sweden to Sidmouth, with a velocity of over fifteen 
miles a second? This is, however, just the velocity of planetary 
matter ; and apparently the most probable explanation of it is 
that it was a cloud of meteorites (‘‘ quite unlike an auroral ray,” 
says Mr. Capron) which just escaped grazing the earth’s surface. 
In this case their velo city would be at least over twenty miles a 
second, moving in about the plane of the earth’s orbit, and 
crossing the earth’s path at least at 45°, or more radially. Per- 
haps some computer will work out the path approximately, a 
other meteors have been so discussed. 
Such a cloud of meteorites must have been at least 130 x 20 miles 
and 20 miles deep if cylindrical, and was apparentiy accompanied 
by a smaller cloud, as seen at Clevedon, As it was seen brightly in 
the moonlight, and yet scarcely dulled the moon in crossing it, 
the visual area of the solid mass might be about a tenth of the 
whole area of the cloud ; so that if the particles were as dark as 
the moon, the cloud would reflect one-tenth as much sunlight in 
an equal visual area. If then the mean diameter of the me 
was but I inch, their volume would equal a sphere of 8o« 
diameter, and would have thrown down a rain of meteors, 
averaging ninety one-inch balls to the square foot, over a district 
about twenty miles across. 
Falling meteors lo e practically all their velocity by friction in 
the atmosphere, before they strike the earth ; since travelling at 
even 15 miles a second, they would be heated to over 
1,000,000° F, 
or by their effects, a sign of a thousandth of this heat. All this 
heat then is pr duced in the air ; and if a meteor strike the 
earth obliquely, it will be checked and fall within a very few 
miles, All the heating of the air must thus take place within a 
small area, in whatever way the meteor may strike. The result 
then of such a meteor cloud as has been just seen, hitting the 
atmosphere (as it only e-caped doing by a quarter of a minute) 
would be to heat the air for some twenty miles in each direction 
to about 10,000° F., or still more if the arrest occurs entirely in 
the upper regions. This hot air would quickly rise, and spread 
the 
out above the cooler atmosphere, causing a great in-suck along | 
the earth from surrounding parts. On the upper surface it 
would quickly cool by radiation into space ; and the effects of 
such a shower to terrestrials would be a terrible gale, blowing 
towards a centre and upwards, with considerable heat radiating 
from above. W. M. FLINDERS PETRIE 
Bromley, Kent, December 2 
CONCERNING the apparition during the aurora of the 17th, 
I ought to have stated the apparent altitude angle between 
it and the moon when at nearest approach, but as the 
angle was larger here than anywhere south, it was more 
difficult to estimate; but I think it was about 12 moon- 
breadths, at the very most or 6” (centre to centre). Also 
I foolishly forgot to note the exact time, but it was 4 or 5 
minutes past 6 p.m. I saw no repetition of the phenomenon for 
5 minutes after, and I then went indoors. It is evident that if 
it was the same object that was seen to transit the moon’s disc 
both at Woodbridge (near Ipswich) and Windsor, that it must 
have followed a path from north-east by east to south-west by 
west (astronomical) since the intersection of its plane of motion 
with the plane containing York, Woodbridge, and Windsor, lies 
in that direction. Most of the observers state that it seemed to 
appear about east, and disappear south of west. Let Y, WW, and 
by arrest, and yet they do not show in them elves | 
B represent York, W ns and Woodbridge respectively in 
their relative positions. C represents Clifton, 
We have Y 8 = 162 miles. 
eae 72. 
BW= on ,, 
CS = FAD" 55 
If it be supposed that the object pursued a wearly straigh? 
path, keeping at a nearly constant height (and this is not incon- 
sistent with the observations), then it ought to have reached its 
greatest angle of elevation along lines drawn perpendicular to 
line B W from each place of observation (it seemed to do so 
at Greenwich, Bedford, and Cambridge, though all the ob- 
servers do not state whether they reckoned by magnetic or astro- 
nomical bearings). ‘The moon was about 8° past meridian, ard 
at York the altitude was about 24°, and at Wocdbridge 26° 
(there being 2° of latitude between). If we consider the angles 
with respect to the p/awe Y B IW, which simplifies matters, then 
elevation at York = 25°, and at Woodbridge the same; and as 
angle between duecicus J’ 42 and YP = 36° ‘Then tan of 
angle of culmination at York will be equal to 
an (25° — 7° , 
(25 : 7) — tan ( Tose sh} 
s 36° 
and tan angle of culm. at Woodbridge will be equal to 
7s ° , 
tan 25” — tan (29° 58’). 
cos 30° 
I am supposing the angle below the moon to be 7° for the 
sake of not exaggerating the height. 
York an! Woodbridge are ina line almost at right angles to 
BW, Then the parallax of the object when seen along this line 
(being the line of culmination) = 29° 58’ — 21° 53’ = 8 5 
about. 
Thus in diagram No. (2) we have— 
Bx = 169 miles x sini(2i 53°) 
sin (8° 5’) 
and required height « P = 
B x sin (29° 58’). 
