142 ANNUAL OF SCIP^NTIFIC DISCOVERY. 



or primary cause to which it may be referred. I am the more encouraged to 

 undertake this labor, from having enjoyed peculiarly favorable opportunities 

 for observing these exhibitions from their commencement, and from having 

 amassed from the accounts published in the periodicals of the day, and from 

 an. extensive correspondence, a greater amount of facts, than, so far as I 

 know, any other person has taken the trouble to accumulate. 



" I know of no other method of successfully investigating a subject of this 

 kind, than first, to examine all the facts of the case ; secondly, to bring to- 

 gether into one view, in separate groups, such as are similar, forming a full 

 and accurate classification ; thirdly, to inquire what general facts these truths 

 reveal, since these deductions form the proximate laws of the phenomenon ; 

 and, finally, to make the laws the groundwork of a general theory, which 

 shall assign the true cause of all." 



The " Secular Period" embraces the exhibitions of the Aurora Borealis 

 during the years 1827, '35, '36, '37, '48, '51, '52, and '53. Professor Olmstead 

 classifies the Auroras by six different names ; Aurora Twilight, the Arches, 

 the Streamers, the Corona, the Waves, and the Auroral Clouds. 



IMPROVED ELECTRICAL AND GALVANIC APPARATUS. 



Breton's Galvanic Battery. A battery arranged by M. Breton, of Paris, for 

 medicinal purposes, is maintained in a constant moisture with chloride of 

 calcium. For one of the poles there is a mixture of copper filings with 

 sawdust, the latter designed to separate the metallic particles, the filings are 

 mixed with a solution of chloride of calcium. The other pole is a similar 

 mixture, in which the copper is replaced by zinc filings. These two prepara- 

 tions placed in a vase, and separated by a porous cell, make a battery, which 

 has always the same intensity of action, on account of its constant humidity, 

 and the indefinite number of its elements. 



Improved Electro-Medical Apparatus. Mr. 'W. P. Piggott, of London, has 

 patented some improvements in galvanic, electric, and electro-magnetic 

 apparatus, and in the mode of then' application as a curative and remedial 

 agent. The inventor constructs a brush consisting of a mixture of bristles 

 and metallic wires or ~plates, or coats a portion of the bristles forming the 

 brush with metal by electric deposition, and these metallic wires, plates, or 

 electrotyped or metallized bristles, communicate with and receive their elec- 

 tricity, galvanism, or electro-magnetism, from a battery or electrical apparatus, 

 fixed in the back, or some other convenient part of the frame, of the brash, or 

 otherwise, as may be required, thus causing what is commonly known as 

 positive or negative currents of electricity to pass from the ends of the w r ires, 

 plates, or metallized bristles, when moved in contact with the hair or skin. 

 Secondly, in the construction of a bath for the administration of galva- 

 nism, electricity, or electro-magnetism, one part of which bath will communicate 

 positive, and the other negative electricity, and this is effected by forming the 

 bath of a combination of elastic or flexible waterproof material and metal, in 

 such a way that when a part of the waterproofing material is caused to enve- 

 lope any required part of the body, two distinct currents of electricity, galva- 

 nism, or electro-magnetism, are created in the same bath. 



