596 TRANSACTIONS OF THE 



On motion, ordered, that " The construction of steam boilers " 

 be continued as tlie question for the next meeting. 

 The Club then adjourned. 



H. MEIGS, Secretary. 



February 25th, 1S57. 



Present — Alderman Haswell, the chairman ; President Pell, 

 Mr. Tillman, Mr. Fisher, Mr. Eutler, Dr. Turner, Mr. Salter, 

 Mr. Pledges, Mr. Chambers, and others. — nearly twenty members 

 in all. 



Mr. Secretary Leonard necessarily absent examining his mills, 

 on the breaking up of this severe winter. 



Mr. Haswell in the chair. Henry Meigs, secretary. 



The Secretary read the following papers translated and pre- 

 pared by him from the latest articles receivea by the American 

 Institute, from Europe and elsewhere, (viz : 



POLARIZATION OF HEAT LIGHTNING. 



Mons. Fleury presented the following extract relative to heat 

 lightning, from a letter from the perpetual secretary, Mons. 

 Liais, viz : 



" I have made experiments on the polarization of heat light- 

 ning, and hitherto have found no trace of polarization; but its 

 absence may be attributed to the feebleness of the light of these 

 lightnings ; for I have found it in brilliant flashes in a heavy 

 thunder storm, reflected the atmosphere. These brilliant flashes 

 gave evident signs of polarization, but those less brilliant did 

 not (on account of their instantaniety,) permit me to see, except 

 with great difficulty,) the difference of the tints. And secondly, 

 I have proven that the light of a very bright flash of lightning, 

 reflected by a cloud, is not polarized. That there is no polariza- 

 tion except when the reflections are made by the air. 



RUHMKORFF'S ELECTRIC MACHINE. 



Experiments. — Take a varnished board, wet your finger and 

 rub it on tlie board so as to form a very thin layer of moisture. 

 Apply the two rheophores (conductors,) at points on this thin 

 stratum of water, three or five inches apart. If the conditions of 

 semi-conductibility are good, the sparks will form more or less 

 zigzags. This experiment is not always .successful, on account of 

 the imperfection of the very thin layer of water on the board. 

 The water must be as thin as possible, and the varnished surface 



