Sept. 30, 1886] 
NATURE 
Bes, 
moves in a path which is like that of the corresponding comet. 
The bodies are, however, now too far from one another to influ- 
ence appreciably each other’s motions. 
(5) The ordinary shooting-stars in their appearance and phe- 
nomena do not differ essentially from the individuals in star- 
showers. 
(6) The meteorites of different falls differ from one another 
in their chemical composition, in their mineral forms, and in 
their tenacity. Yet through all these differences they have pecu- 
liar common properties which distinguish them entirely from all 
terrestrial rocks. 
(7) The most delicate researches have failed to detect any trace 
of organic life in meteorites. 
These propositions have practically universal acceptance among 
scientific men. We go on to consider others which have been 
received with hesitation, or in some cases have been denied. 
With a great degree of confidence, we may believe that shoot- 
ing-stars are solid bodies. As we see them they are discrete 
bodies, separated even in prolific star-showers by large distances 
one from another. We see them penetrate the air many miles, 
that is, many hundred times their own diameters at the very 
least. They are sometimes seen to break in two. They are 
sometimes Seen to glance in the air. There is good reason to 
believe that they glance before they become visible. 
Now these are not the phenomena which may be reasonably 
expected from a mass of gas. In the first place a spherical mass 
of matter at the earth’s distance from the sun, under no con- 
straint, and having no expansive or cohesive power of its own, 
must exceed in density air at one-sixth of a millimetre pressure 
(a density often obtained in the ordinary air-pump), or else the 
sun by his unequal attraction for its parts will scatter it. Can 
we conceive that a small mass of gas with no external restraint 
to resist its elastic form, can maintain so great a density ? 
But suppose that such a mass does exist, and that its largest 
and smallest dimensions are not greatly unequal ; and suppose 
further that it impinges upon the air with a planetary velocity ; 
could we possibly have as the visible result a shooting-star ? 
When a solid meteorite comes into the air with a like velocity, 
its surface is burned or melted away. Iron masses and many 
of the stones have had burned into them those wonderful 
pittings or cupules which are well imitated, as M. Daubrée has 
shown, by the erosion of the interior of steel cannon by the 
continuous use of powder under high pressure. They are imi- 
tated also by the action of dynamite upon masses of steel near 
which the dynamite explodes. Such tremendous resistance that 
mass of gas would have to meet! The first effect would be to 
flatten the mass, for it is elastic; the next to scatter it, for 
there is no cohesion. We ought to see a flash instead of a long 
burning streak of light. The mass that causes the shooting-star 
can hardly be conceived of except as a solid body. 
Again, we may reasonably believe that the bodies that cause 
the shooting-stars, the large fire-balls, and the stone-producing 
meteor, all belong to one class. They differ in kind of 
material, in density, in size. But from the faintest shooting- 
star to the largest stone-meteor, we pass by such small grada- 
tions that no clear dividing lines can separate them into classes. 
See wherein they are alike :— 
(1) Each appears as a ball of fire traversing the apparent 
heavens, just as a single solid but glowing or burning mass 
would do. 
(2) Each is seen in the same part of the atmosphere, and 
moves through its upper portion. The stones come to the 
ground, it is true, but the luminous portion of their paths 
generally ends high up in the air. 
(3) Each has a velocity which implies an orbit about the sun. 
(4) The members of each class have apparent motions which 
imply common relations to the horizon, to the ecliptic, and to 
the line of the earth’s motion. 
(5) A cloudy train is sometimes left along the track, both of 
the stone-meteor, and of the shooting-star. 
(6) They have like varieties of colours, though in small 
meteors they are naturally less intense and are not so variously 
combined as in large ones. 
In short, if the bodies that produce the various kinds of fire- 
balls had just the differences in size and material which we find 
in meteorites, all the differences in the appearances would be 
explained ; while, on the other hand, a part of the likenesses that 
characterise the flights point to something common in the astro- 
nomical relations of the bodies that produce them. 
This likeness of the several grades of luminous meteors has 
not been admitted by all scientific men, Especially it was not 
accepted by your late President, Prof. J. Lawrence Smith, who 
by his studies added so much to our knowledge of the meteor- 
ites. The only objection, however, so far as I know, that has 
been urged against the relationship of the meteorites and the 
star-shower meteors, and the only objection which I have been 
able to conceive of that has apparent force is the fact that no 
meteorites have been secured that are known to have come from 
the star-showers. This objection is plausible, and has been 
urged, both by mineralogists and astronomers, as a perfect reply 
to the argument for a common nature to all the meteors. 
But what is its real strength? There have been in the last 
hundred years five or six star-showers of considerable intensity. 
The objection assumes that if the bodies then seen were like 
other meteors we should have reason to expect that among so 
many hundreds of millions of individual flights a large number 
of stones would have come to the ground and have been 
picked up. 
Let us see how many such stones we ought to expect. A 
reasonable estimate of the total number of meteors in all of these 
five or six star-showers combined makes it about equal to the 
number of ordinary meteors which come into the air in six or 
eight months. Inasmuch as we can only estimate the numbers 
seen in some of the showers, let us suppose that the total 
number for all the star-showers was equal to one year’s supply 
of ord:nary meteors. Now the average annual number of stone- 
meteors of known date from which we have secured specimens 
has, during this hundred years, been about two and a half. 
Let us assume, then, that the luminous meteors are all of like 
origin and astronomical nature ; and further assume that the 
proportion of large ones, and of those fitted to come entirely 
through the air without destruction, is the same among the star- 
shower meteors as among the other meteors. With these two 
assumptions, a hundred years of experience would then lead us 
to expect two, or perhaps three, stone:falls from which we secure 
specimens during all the half-dozen star-showers put together. 
To ask for more than two or three is to demand of star-shower 
meteors more than other meteors give us. The failure to get 
these two or three may have resulted from chance, or from some 
peculiarity in the nature of the rocks of Biela’s and Tempel’s 
comets. It is very slender ground upon which to rest a denial 
of the common nature of objects that are so similar in appear- 
ance and behaviour as the large and small meteors. 
It may be assumed, then, as reasonable that the shooting-stars 
and the stone-meteors, together with all the intermediate forms 
of fire-balls, are like phenomena. What we know about the 
one may with due caution be used to teach facts about the other. 
From the mineral and physical nature of the different meteor- 
ites, we may reason to the shooting-stars, and from facts esta- 
blished about the shooting-stars we may infer something about 
the origin and history of the meteorites. Thus it is reasonable 
to suppose that the shooting-stars are made up of such matter 
and such varieties of matter as are found in meteorites. On the 
other hand, since star-showers are surely related to comets, it is 
reasonable to look for some relation of the meteorites to the 
astronomical bodies and systems of which the comets form a 
part. 
This common nature of the stone-meteor and the shooting- 
stars enables us to get some idea, indefinite but yet of great 
yalue, about the masses of the shooting-stars. Few meteoric 
stones weigh more than 100 lbs. The most productive stone- 
falls have furnished only a few hundred pounds each, though the 
irons are larger. Allowing for fragments not found, and for 
portions scattered in the air, such meteors may be regarded as 
weighing a ton, or it may be several tons, on entering the air. 
The explosion of such a meteor is heard a hundred miles around, 
shaking the air and the houses over the whole region like an 
earthquake. The size and brilliancy of the flame of the ordinary 
shooting-star is so much less than that of the stone-meteor that 
it is reasonable to regard the ordinary meteorvid as weighing 
pounds, or even ounces, rather than tons. 
Determinations of mass have been made by measuring the 
light and computing the energy needed to produce the light. 
These are to be regarded as lower limits of size, because a large 
part of the energy of the me'eors is chanzed into heat and 
motion of the air. The smaller meteors visible to the naked 
eye may be thought of without serious error as being of the size 
of gravel stones, allowing, however, not a little latitude to the 
meaning of the indefinite word “gravel.” 
These facts about the masses of shooting-stars have important 
