IN offering to the Subscribers the closing Number of the First Volume of the King's College Literary and Scientific Magazine, the Editors feel it their duty to express their gratitude for the prompt support which has enabled them to commence and carry it on with success. Having now, as they hope, set the Magazine on a substantial basis, they contemplate an endeavour to meet the numerous suggestions they have received from the Subscribers as to enlarging the Magazine; and for the future they hope to publish it as a regular Quarterly Journal. They propose devoting a portion of each Number to reviews, another to original articles, a third to poetry and light reading, and to give also reports of the proceedings of the transactions of the literary and scientific societies in connexion with King's College. In this endeavour to meet the general wish, the Editors trust they shall meet with the co-operation of the Subscribers, and be enabled to render the Magazine worthy of the College whose name it bears. King's College Magazine. JUNE 1, 1849. On a New Method of Observing with a Transit Instrument placed nearly, but not exactly, in the Meridian Plane. By the Rev. Professor O'Brien. 1. It is by no means an easy thing to observe the time of transit of a star across the meridian by means of a chronometer (or clock), and a transit instrument with three, five, or seven vertical wires in the focus. If the star always came on the middle wire exactly at a tick of the clock, there would be no difficulty in determining the exact second of its transit; but this not being the case, and it being necessary in consequence to observe the transit of the star over several vertical wires-at none of which it usually arrives exactly at a tick of the chronometer-it requires some practice to observe a transit well; and even with practice the observation is subject to some error, which, though small, should not be allowed to exist in an instrument capable of such exactness and perfection as the transit instrument. The following method of observing has the advantage of causing the star to be seen on the wire exactly at a tick of the chronometer, and it requires but a single vertical wire in the focus. Besides, it has the advantage of observing the exact time of transit of the star across the meridian, though the instrument be not placed truly in that plane; and it dispenses with the use of the common formula for the deviation, which requires the latitude and the star's polar distance to be known, at least approximately. 2. For the application of this method there is to be but one vertical wire in the focus; but the horizontal Y must be made to move evenly and easily by means of a fine micrometer screw with a graduated head, accessible to the observer's hand while he is looking through the telescope. The chronometer is, for simplicity, supposed VOL. I. NO. I. B |