1917-18.] Note on the Strathmore Meteorite of 1917 Dec. 3. 71 
upon which it fell, nor did it char the wood through which it broke. A 
second, also upwards of 2 lbs. in weight, fell in a field at Carsie Farm, 
about 20 yards from where Mrs Welsh, the wife of the tenant, was 
standing, and penetrated the frozen soil to a depth of 4 inches. This was 
picked up about a quarter of an hour after, and was not noticeably warm. 
The third, a large fragment weighing 22J lbs., fell in a field at Easter 
Essendy Farm, east of Loch Marlee. A foreman working 200 yards away 
heard the sounds, and then noticed some sheep in the field start and run 
away. After the news of the other discoveries, he went to the spot and 
found the stone embedded in a hole about 20 inches deep, the clod and 
pebbles thrown up on the N.W. side. A small chip was fractured from 
one corner of it. 
The foregoing particulars, all of which I have verified personally or by 
letters, contain no novelty in the history of these bodies. 
The Carsie fragment and the Essendy fragment are now in the collection 
of the Royal Scottish Museum. 
I would add a few remarks on the physics of the arrival on the earth 
of a meteorite of this kind. 
The sound of its explosions arrived “ some minutes ” before the fragments 
fell. Hence the mean speed of these fragments between explosion and 
arrival was less than the mean velocity of the sound, which in the rarer 
strata of the atmosphere would be much reduced. It is therefore evident 
that the velocity of arrival of the stones, which would be the lowest 
velocity in their course, must have been a moderate fraction of the 
ordinary velocity of sound (1100 ft./sec.), perhaps not more than 200 or 
300 ft./sec. For each 100 ft./sec. by which the mean velocity of sound 
exceeded that of translation of the meteorite, and for each minute that 
elapsed between the explosion and arrival, we must remove the point of 
explosion IT miles from the point of fall. Say five minutes and 500 ft./sec. 
across, and we have 28 miles, which would place the explosion 20 miles 
away horizontally and 20 miles high. Numbers in this neighbourhood are 
fairly in agreement with the record. As to the speed with which it entered 
the earth’s atmosphere, there is practical^ nothing to go upon, for it has 
no relation to the speed on arrival at the earth, and whatever it was it 
would be reduced in a few seconds to very moderate dimensions. Suppose, 
for example, it was n miles per second. We may take it that the air 
would not have time to slip away from in front of the projectile to any 
considerable degree, so that after 1 sec. it would be driving in front of it 
a mass of n miles of air in a compressed state and sharing with it its 
momentum. Let the projectile be of depth c feet, density p , and the air of 
