NATURAL PHILOSOPHY. 119 



OX THE DISCHARGE OF ATMOSPHERIC ELECTRICITY THROUGH 



GAS-PIPES AND MAINS. 



In a paper on the above subject read before the American Association, at 

 Springfield, 18-5'), by Prof. B. Silliman, Jr., the author stated that, in June 

 1858, a thunder-bolt fell on the spire (227 feet high) of a church in New 

 Haven, and was conducted by a rod to a point less than 2-5 feet from the 

 ground. Here, owing to an imperfect arrangement of the rod, it passed 

 through a brick wall 20 inches thick, to a gas-pipe on the wall opposite. By 

 the new channel thus forcibly gained, the discharge was conducted to the 

 main pipes of distribution, and no further immediate effects were seen. Soon 

 afterwards, however, the escape of gas on the street in front of the church 

 was noticed, as well by the odor as by the death or the sickly condition of the 

 shade-trees lining the street. Upon opening the ground, it was found to be 

 saturated with gas, and every joint in the whole length of the street, some 

 forty in number, was discovered to be leaking profusely. The inference 

 seemed unavoidable that the leakage was occasioned by the electrical dis- 

 charge. 



During the last week of July 18-39, another very energetic discharge fell 

 upon a house in George Street, Xew Haven, which was supplied with gas, 

 and while but little injury was done to the dwelling, and none at all to its 

 inhabitants, the gas mains in the whole street, to the number of over sixty 

 joints, were found to be leaking profusely. In June of this year, the new 

 church spire struck in 18-58, was again the subject of a second accident of 

 this sort; the wall of brick was again perforated near the same place, and in 

 the same manner as last year, with the additional circumstance that the gas- 

 pipe in the church was fused or burnt off at the point of contact of the 

 escaping discharge, and the gas being thus set on fire, in its turn set fire to 

 the Avail casing behind which it ran. But- either because the violence of the 

 discharge was less than last year, or because a portion of it found a lateral 

 escape, there was no effect produced in disturbing the joints of the street 

 mains. 



This effect Prof. Silliman thought was plainly to be referred to the sudden 

 expansion of the gas in the main, at the point of electrical discharge. Not- 

 withstanding the enormous extent of the metallic circuit, over 20 miles of 

 pipe from 3 to 12 inches in diameter all buried in moist earth, the restora- 

 tion of electrical equilibrium could not be so accomplished x without this 

 hitherto unobserved effect of expansion on the gas in the mains. 



Prof. Henry remarked, that the introduction of gas-pipes into our houses 

 brought a new source of danger to human life from electrical discharges. 

 The rod should not merely terminate in the earth, but he had been in the 

 habit of recommending that it be placed in connection with the water or gas- 

 pipes. 



DAMAGE BY LIGHTNING AT SEA. 



Sir W. Snow Harris, under the direction of the House of Commons, has 

 published a list of the ships of the Royal Xavy damaged by lightning be- 

 tween the years 1790 and IS 10. The list, although not complete, embraces 

 no less than 280 cases, the particulars of which are full and reliable. These 

 cases include 106 ships of the line, 70 frigates, 80 sloops and brigs, 2 pr-lioon- 

 ers, 7 cutters, 5 hulks, 5 ships in ordinary, 5 steamers, two of which were 



