PROF. C. C. TROWBRIDGE, of New York, has been conducting an interesting investigation, during recent years, into the heights and velocities of the streaks and trains of meteors. He has been collecting old records of these phenomena, and will be glad to receive any new materials which may be gathered during this year's Perseid shower. Every year brings us some brilliant Perseids leaving durable streaks, and it is important that when these appear the drift amongst the stars should be noted at short intervals. In the case of a streak enduring ten minutes, a series of diagrams showing the positions of the streak and neighbouring stars every two minutes would be valuable.