A series of astronomical observations have been simultaneously commenced under the directions of the Coast Survey, at the Dudley Observatory, Albany, and Mr. Rutherford's private observatory in Second avenue, this city. Each observatory is furnished with an astronomical clock, a recording register and a transit instrument. A galvanic current is constantly passing through each clock from a battery outside, and this current is interrupted at every beat of the pendulum, and the clock is made to record its own vibrations upon the register. When the atijiosphere is clear at Nevir York and Albany, the stations being connected by telegraph, the clock at the latter city is put into the galvanic circuit and its beats are heard at the same instant in New York. When a star passes the meridian at Albany, the astronomer there, as it crosses the thread of his transit instrument, strikes his key, and the observation is recorded telegraphically on the registers at both stations. When the same star reaches the meridian at New York, the observer telegraphs its passage to Albany, and thus the passage of each star as it is seen at the two different stations ia recorded in both places. In this way an accurate comparison of the times of the two cities is made. When several observations have been first made at Albany, the astronomical clock at New York is put into the circuit, and the operations continued back and forth in order to obtain perfect accuracy. Hints in Season.—Always sign your name and give the full Post Office address in every letter you write. Do not be afraid of too much definiteness upon this matter—many letters sent to us cannot be answered for want of it. If you expect an answer by mail inclose a stamp to prepay return postage—this is no more than fair. If you send a model attach to it a paper, card, or have your name and residence marked on it; this will save a great deal of trouble. Prepay express charges when it is possible to do so ; when it is not, remit an amount sufficient to cover the expense. By observing these simple rules every- , thing will go pn smoothly. ^