212 F. C. Robinson — On the Northford Meteorite. 



the magnitude of the deflection, and was as great as one centi- 

 meter, at the end of two or three minutes, for a deflection of 

 twenty centimeters. The suspending fiber had been in the 

 instrument for some time, inquiry showed that it was drawn 

 from floss silk.* On substituting a fiber drawn from cocoon silk 

 which had been well washed, no displacement of the zero was 

 observed except where the room had been kept at about 0° C. 

 for several hours. Some trouble was experienced from sudden 

 movements of the needle, apparently caused by the working of 

 a dynamo, from which wires extended through the various parts 

 of the building in close proximity to the pipes for gas and 

 water, the pipes being made use of as ground connections for 

 the electrometer and batteries. These deflections of the needle 

 were most marked in the cold, dry weather of winter ; from 

 this it seems probable that the pipes did not serve as very good 

 ground connections at the time and under the circumstances. 

 Jefferson Physical Laboratory, Dec. 5th, 1887. 



Art. XVIII. — On the so-called Northford, Maine, Meteorite/ 

 by F. C. Robinson. 



Vaeiotts cabinets in this state and doubtless elsewhere con- 

 tain specimens of a black rock showing signs of external fusion, 

 labeled " Meteorite which fell in Northport, Maine." A speci- 

 men recently received from Mr. "W. H. Sargent, of Brewer, 

 Maine, has been analyzed in my laboratory by Mr. Charles 

 Fish, with the following results : 



SiOo S P Mn 



7>55 



The Mg, Al and most of the Fe were evidently combined 

 as silicates. The rest of the Fe was present as sulphide and 

 oxide, and the copper as sulphide. Calculating them as such 

 the analysis comes up to 98*36 per cent omitting the small 

 amount of P, Co, Mn. The piece I have and others I have 

 seen are nearly or quite black in color, and seem to have been 

 broken from a nearly spherical mass of about l-§- or 2 feet in 

 diameter, whose outer surface was fused. Sections under the 

 microscope closely resemble those made from furnace slag from 

 the reduction of iron or copper ore. It will be noticed too 

 that the analysis corresponds quite closely to some published 

 analyses of slag. (Compare " Kerl's Handbuch," p. 856, vol. i.) 



* Boltzmann, Pogg. Ann., cli, p. 487. Ayrton and Perry, Jour. Tel. Engineers, 

 vol. v, p. 481. 



Fe 



Al 



Cu 



Mg 



Co 



Si0 2 



S 



P 



Mn 



3-37 



4-19 



0-88 



2-05 



0-25 



27-68 



1-10 



0-03 



tr 



