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 proved emphatically by their structure, which is incompatible with the supposition that the body possessing it has originated in a comet.

I would specially commend the important researches of Tschermak to those interested in meteorites. In the museum at Vienna there is a collection of meteorites rivalling our own splendid collection in the Natural History Museum at South Kensington. The eminent Austrian Professor has made an elaborate study of the different bodies of this class in the various museums, and he has come to the conclusion that meteorites have been derived from volcanoes on some large celestial body. So far as I am aware, no other mineralogist has maintained an opinion of an opposite character to that entertained by Tschermak. We may, therefore, inquire where the volcano must have been situated so that the missiles it projects should tumble down on our earth. Placed in this aspect the problem is no longer one for geologists or of mineralogists. It has now come within the province of astronomers and mathematicians. It is for them to say where, in all probability, those volcanoes have been situated from which the meteorites have come. This is indeed a very interesting question, and I propose to undertake its solution.

The missile from a cannon discharged vertically upwards will fall back to earth with a speed nearly as great as that with which it was projected. In fact, the speed at the return would be quite as great as the speed at the departure were it not for the resistance of the atmosphere. Under the actual circumstances of this globe, and with the actual strength of our artillery, and the potency that any available explosives may possess, we are not able