168 THE AMERICAN MONTHLY [July, 



terrace, where it collects in little black heaps, not unlike gun- 

 powder. It also gathers about the spouts which carry off the 

 rain-water. An old friend of mine, Mr. Charles Blechynden, 

 who has resided in India for many years and who still takes a 

 keen and fresh delight in natural science, told me recently that he 

 found that by plunging a powerful horseshoe magnet into a 

 handful of our black ' terrace dust ' minute particles were at- 

 tracted to the magnet poles, which he surmised might prove to 

 be meteoric dust. I have improved on Mr. Blechynden's pro- 

 cess ; with a camel's hair brush I brush off the dust from the poles 

 onto a sheet of thin white paper, and then by drawing the mag- 

 net backward and forward under the paper I draw away the iron 

 particles, which are thus practically twice magnetically sifted. 

 On mounting these twice-sifted particles in balsam and placing 

 them under a microscope, I find the material includes a few spheri- 

 cal bodies ; some are opaque and of a black or rusty red color, 

 while others are transparent spheres, wdiich enclose bubbles as 

 well as patches of dark granular matter. The dark spheres re- 

 mind one, when examined with a half-inch, of small shot;' and 

 their spherical form suggests that, like small shot, they were once 

 in a state of fusion and have dropped from a considerable height, 

 a view which is supported by the glassy spheres enclosing minute 

 bubbles. If this magnet-attracted dust, which is obviously iron, 

 is neither meteoric nor volcanic in its origin, what is it.? 



" To the best of my recollection I have never seen nor heard 

 of the magnet being used as a means for collecting meteoric dust, 

 though it is so obvious that it seems likely to have suggested 

 itself to others. It certainly furnishes us with a simple and relia- 

 ble method of separating from the dust collected on house tops 

 the iron particles in it ; and if the particles so obtained are me- 

 teoric or volcanic, then Mr. Blechynden's device will enable 

 observers all the world over to collect this material, and to in- 

 stitute comparative observations with the view of determining at 

 what seasons of the year, and in what localities, most of this 

 spherical iron dust falls. I have already obtained it from three 

 places — my friend's house at Alipore, the roof of my own 

 residence, and the roof and tower of the High Court here. My 

 house is a mile and a half from the High Court, while Alipore 

 is three miles from reach of the above localities ; indeed a triangle 

 described so as to include each of the three points named would 

 roughly be an isosceles triangle, with the line joining my house 

 and the High Court for its base. The terrace of the Court- 

 house is proljably quite a loo feet, and the roof of its tower about 

 1 60' feet above the ground. The dust sent is from the roof of 

 my house. The magnetic method of getting at these meteoric 

 or volcanic particles may be well known ; if so, no harm can be 

 done in calling attention to it in this brief note. If the method 

 be new, my friend Mr. Blechynden has done a service to 

 science." 



