166 ANXTAL OF SCIENTIFIC DISCOVERT. 



cluster 2G4 feet above. Owing to the heij^ht, a gas regulator is 

 proviilod at the stop-cock of each tier, which equalizes tlie flow. 

 Ko. 10 copper wires are used throughout; and, after being 

 wrapped with linen, are inclosed in India-rubber tubing, and 

 incased, or otherwise secretly laid, passagt!s in the walls being 

 drilled therefor through a thickness of from 3 to 20 feet. The 

 return circuit is made through the gas })ipes, saving a duplication 

 of the nine thousand 3ards of wire. The burners used have an 

 indestructil)le lava ti|), which acts as an insulator, and each is 

 provided with an insulated coil of jdatinum wire on one side of 

 tlie orilices, so as not to interfere with the free exit of the gas, 

 while exposing one side of the jet to the action of the red-hot 

 metal when the electric connection is made. 



The experiments liave covered a period of nearly ten years, and 

 six patents cover the main features of the invention. The ex- 

 periments, on so grand a scale as the Capitol dome, with 1100 

 burners, at such distance and elevation, settle the question of 

 success; and the invention will come into general use for lighting 

 theatres, concert and public halls, and eventually, by large central 

 batteries, will ramify over city districts, to aiibrd to residents, 

 merchants, and manufacturers, a connection for the purpose of 

 iustautaucous illumination to any extent desired. — Sciait. Am. 



PROTECTION AGAINST LIGHTNING. 



The present summer, so far, has been remarkable for the num- 

 ber of accidents from discharges of electricity. We believe there 

 has been no storm this season, accompanied with lightning, which 

 has not resulted in damage to person or proj^^rty. In view of 

 tliese facts, the importance of providing adequate protection to 

 buildings and ships, from lightning, can hardly be over-estimated. 

 The failure of lightning-rods, in some instances, to protect the 

 structure to which they were attached, has had the effect to im- 

 pair confidence in such means of protection ; but it can be clearly 

 demonstrated that, when made on scientific principles, honestly 

 consti'ucted, and properly applied, they are the only means which 

 can be relied upon for protection, and that they are deserving of 

 entire confidence. 



The electric fluid does not always descend in a vertical path, 

 nor in a coui'se approaching that direction. Many instances are 

 on record where the bolt travelled horizontally, and much dam- 

 age has occurred from "earth strokes" or ascending discharges. 

 These facts have not alwa\"s been recognized by constructors of 

 lightning-rods, their idea being that a building was sufliciently 

 insured against lightning by having the rods jiroject above the 

 highest poilion of the building, leaving all the other parts unpro- 

 tected. Experience has added its evidence to the instructions of 

 science in demonstrating the unreliability of such protectors. 



From Lyon's " Treatise on Lightning-Conductors," we copy the 

 following requisites of a good rod : — 



"1. The conductor should be made of good conducting sub- 

 stance. 



