84 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



ELECTRICAL PHENOMENA. 



Dr. Munk, of Marburg, quotes a sentence from the Talmud 

 [Tosefta, Sabbath VII.) showing that in the fourth and fifth 

 centuries before Christ the use of the li^htnin^-rod was un- 

 derstood. Dr. Wiedemann adds that, according to Dumi- 

 chen, the Egyptians gilded and coppered the highest projec- 

 tions, etc.," in order to protect from the celestial lightning." 



The protection of buildings from lightning has been treat- 

 ed of recently by the eminent electrician J. C. Maxwell, who 

 elucidates the idea, already defended in these pages, that a 

 discharge cannot occur between two points within a build- 

 ing if the exterior is surrounded by a metal cage or sheath- 

 ing, which latter need not be connected with the ground, but 

 must, however, be joined to the gas or water pipes, in case 

 any such enter into the building from without. 



In a memoir upon the aurora of April 7, 1874, published in 

 the report of the Chief Signal Officer for 1876, the author 

 concludes that the auroral light emanated from a very low 

 region in the earth's atmosphere, and spread east and west 

 from certain well-marked localities. 



An elaborate paper by Mann is reprinted with additions 

 in the Papers on Professional Engineering. 



RELATIONS WITH SUN-SPOTS. 



The connection between solar-spot frequency and terres- 

 trial phenomena has continued to receive some attention 

 during the year, but not much progress has been made by 

 the advocates of an intimate connection. Meld rum reports 

 that the cyclones of 1876 in the Indian Ocean exhibited 

 markedly diminished intensity, in accordance with his theory; 

 Hunter, Hill, and Archibald have shown that the registers for 

 different parts of India may be so construed as to lend 

 plausibility to the idea that years of maximum and minimum 

 rainfall follow the years of maximum and minimum sun-spot 

 activity. The importance of the question in India is acknowl- 

 edged in view of the disastrous famines that visit that land, 

 and the British Government has been urged, through the 

 London daily press, to institute a comprehensive system of 

 hydraulic engineering, such that the surplus rains of one sea- 

 son may be husbanded for use in time of need. Such a sys- 



