40 On the Magnetic Injiuence of the Lunar Spectrum. 



results of experiments, from which in part those views have 

 been deduced, should be corroborated by some of those emi- 

 nent men who have devoted their lives to scientific pursuits, 

 — after rigid, and, I would hope, impartial investigation. 

 I am. Gentlemen, vours faithfully, 



F. W. De Moleyns,'M.A. 



1. Having lately made some interesting observations upon 

 the magnetic injiuence of the lunar spectrum, which may tend 

 to the establishment of a new theory of magnetism, I venture 

 to submit them to the many natural philosophers who read 

 the Philosophical Magazine, in the hope that they may lead 

 to other inquiries upon the same subject. 



2. The hypothesis of Dr. Morichini, that the blue and vio- 

 let rays of the solar spectrum were capable of imparting mag- 

 netic qualities to needles which were exposed to their in- 

 fluence, has been contested by several practical physicists, 

 who have failed in obtaining the desired result when they 

 adopted his method of making the experiment. Being de- 

 sirous of satisfying myself by personal observation upon this 

 question, I placed a sewing needle with care upon the sur- 

 face of a cup of water, and found that it developed a polarity 

 without any preliminary exposure to the prismatic rays of the 

 sun, by arranging itself in the plane of the magnetic meridian 

 "with its thinnest i^art or jioint towards the north, and its head 

 or thickest part towards the south. 



3. The experiment was frequently repeated with different 

 needles, and the result was always the same, unless the head 

 of the needle was more than usually thin ; the inference be- 

 ing, that the polarity of the needle was governed by a law 

 which made the end having the least bulk a north pole. It 

 is probable that Morichini was not aware of the fact, that a 

 polarity existed in a needle independently of any such mag- 

 netizing influence, and that he supposed its ordinary polarity 

 to have been produced by his exposing it to the refracted rays 

 of the sun. 



4. But such an exposure occasioned an important change 

 in its magnetic properties; for having removed it from the 

 surface of the water, and placed it on a table in the blue 

 rays, where it remained for about five minutes, I found that 

 when it was again made to float upon the water, it assumed 

 a polarity opposite to that above mentioned, with its head 

 instead of its point directed towards the north magnetic pole 

 of the earth. 



5. This experiment, repeated in various ways with different 

 needles, always offered the same result : — 1 . The point was 



