1848.] Miscellaneous. 15/ 



break, plunged, at the distance apart of about an inch, into a tumbler 

 of water ; though the electricity would readily pass through hundreds 

 of miles of moist earth, not the least quantity appeared to be trans- 

 mitted by the inch of water in this arrangement. The explanation 

 does not appear to be difficult. In this case the quantity of conducting 

 matter was not sufficient to allow of the lateral expansion of the elec- 

 trical currents necessary to the diminution of the resistance of the 

 water. 



Another obstacle to the operation of the telegraph in this country is 

 the indicative influence of every flash of lightning which takes place 

 within many miles of the line of conductors. You have probably seen 

 my report on this subject, made to the American Philosophical Society 

 and republished in the Philosophical Magazane last winter. I regret that 

 I have not been able as yet to find a copy to send you.* 



You have perhaps seen an account of my researches on the spots of 

 the sun by means of the thermo-electrical apparatus, and an image of 

 the luminary in a dark chamber. I have since applied the thermo-pile 

 to the eye-end of a large reflecting telescope, and the combination has 

 given me an instrument of such delicacy that I can detect the heat of 

 a man's face at the distauce of several hundred yards. The smallest 

 cloud will give a deflection of the needle of 30 degrees. I have intended 

 to apply this arrangement to the exploration of the heavens for differ- 

 ences of temperature in the celestial vault ; and a few observations I 

 have made give some interesting results, but my engagements have 

 been such that I have been unable to follow them up. 



I think I informed you in a former communication that I had worked 

 out fully, the cause of the phenomena of the lateral discharge ; but I 

 am ashamed to say that my paper in full on this subject has not yet 

 been published. I have from time to time given the facts to the Ame- 

 rican Philosophical Society and they have appeared in the different num- 

 bers of the proceedings of this body. You will find some of my results 

 mentioned in my report on the wires of the telegraph, a copy of which 

 I have been so fortunate as to find, and which you will receive in the 

 package I send you. 



I have to regret that the articles I send you are not more worthy 

 your acceptance ; they are such as were on my table at the time I re- 

 * 1 have since found a copy, which I enclose in the package. 



