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Meeting of Astronomers at Buffalo.-A correspondent suggests the possibility of a convention of astronomers to be held in connection with the PanAmerican Exposition which is to be in the city of Buffalo, N. Y., May 1 to Nov. 1, 1900. It is possible that such a meeting could be secured, if the matter were planned for soon. We would gladly receive suggestions from our readers who are interested in such a convention.

Professor W. H. Wilson at Wooster, Ohio.-Our readers will be interested to learn that Professor W. H. Wilson, who has been connected for some time with Geneva College, at Beaver Falls, Pa., has accepted the position of Professor of Mathematics in the University at Wooster, Ohio, and has already begun his work in the new position.

His duties include, for the present, Dr. S. J. Kirkwood's astronomical work as well as the mathematics during Dr. Kirkwood's illness.

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During the last year and a half, some astronomers have expressed opinions, with more or less assurance, that the path of the Leonid stream of meteors has been so changed, that we may no longer hope for such grand showers as were seen in 1866 and notably in 1833. Particular attention was called to this possibility and even probability, by a paper presented before the Royal Astronomical Society, March 2, 1899, by G. Johnstone Stoney and A. M. W. Downing, an abstract of which was printed in The Observatory, for May, 1899. In that paper it was said that Professor J. C. Adams' object in investigating the Leonid orbit was to determine the shift of the nodes of the orbit due to the disturbances by the planets and to compare the calculated amount with that obtained by Professor H. A. Newton, of Yale College, from a study, which he had made, of observations at intervals during the last thousand years. Professor Adams, of England, gave attention to this interesting piece of mathematical work about 30 years ago, using what is known as the method by Gauss for computing perturbations. Mathematicians esteem it a method of great elegance, because it "furnishes the average amount of each perturbation on the supposition that the periodic times of the disturbed body and the disturbing planet are incommensurable, so that in the course of time, the two bodies present themselves in every possible position in relation to one another." It will readily be seen that these conditions could be only imperfectly fulfilled in the short period of 1000 years from which time all available observations were secured, and so results obtained from the most excellent of methods would be incomplete for obvious reasons.

The three planets which influenced the path of the Leonids most during the last period of revolution of the stream were Jupiter, Saturn and Uranus. If we remember that 14 revolutions of Jupiter equal 5 revolutions of the Leonids within about one-fifth

of a year; that 2 revolutions of Uranus equal the same time within two years, and that 9 revolutions of Saturn equal 8 of the Leonids within a fraction of a year, it will be easy for any reader to understand how the attraction of these great planets when near the thickest part of the stream will certainly change its course.

Now, since these cycles of planetary attraction have been several times repeated during the 1,000 years already referred to, it is known that the points of intersection of the Earth's orbit with that of the Leonids has oscillated about a mean value of the advance of the node, so that predictions of showers dependent on this mean motion have usually varied several hours from the times of their actual occurrence. In the article referred to, one instance is mentioned in which the computed time was twentysix hours later than the appearance of the shower. This occurred in the year A. D. 1533. Some computations for the present century have furnished results showing as great a difference between the forecast and the actual shower, as in this instance, but, in the opposite direction.

From these and other facts like them it must be evident that the problem of determining the exact position of the orbit of the Leonids for any date is a very difficult one. Astronomers are fully aware of this, and they have given earnest attention to its study for some years past, and they are still at work on the details of the problem which seem almost endless in kind and variety.

It may be instructive to the ordinary reader to have a few more points in outline to get a fuller view of the nature and extent of the problem. In order to predict the coming of a great Leonid shower satisfactorily, it will be necessary to know the actual amount of the perturbations in each revolution of the swarm of meteors, and also for meteors occupying various stations along the path of the stream, so as to determine its course in space as definitely as possible. The dense part of the stream is called the ortho-stream, which means the great body of the Leonids travelling around the Sun, in nearly a compact swarm of such length that it requires about three years for the whole train to pass the point of intersection which the Leonid orbit makes with that of the Earth; but on account of the inclination of the two orbits the time that is required for the Earth to pass through the ortho-stream each year is only five or six hours. There are also other Leonid meteors that have fallen behind, or are in advance of the parent stream, so that all parts of the

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