424 



LIGHTNING-RODS. 



tacked by the Grebos, simultaneously at four 

 different points. After a determined contest 

 lasting eight hours the Grebos were repulsed, 

 with considerable loss, at all points. The loss 

 of the Liberians was six killed and an unknown 

 number wounded. In another battle, on Oc- 

 tober 10th, at Harper, the Liberians were to- 

 tally routed, abandoning their artillery and 

 ammunition. The American minister resident, 

 Mr. J. M. Turner, reported that the Grebos 

 were armed with excellent Snyder rifles, and 

 it is reported from other sources that the Brit- 

 ish ships trading in those waters were supply- 

 ing the natives with munitions of war. Mr. 

 Turner also expressed the opinion that the 

 Grebos could raise from 5,000 to 7,000 able 

 fighting men, while the Government troops 

 numbered about 1,000 men. In December sev- 

 eral native tribes, encouraged by the success 

 of the Grebo tribe, made an attack on the set- 

 tlers in another part of Liberia, but were vig- 

 orously repulsed. A private letter said that 

 the peace of the republic was somewhat dis- 

 turbed by the question of color. President Rob- 

 erts was much embarrassed on this account, 

 the fact of his not being of pure African blood 

 being objectional to many who are. An intel- 

 ligent negro from the West Indies was the 

 principal agitating spirit, who sought to estab- 

 lish a political color-test, taking the side of the 

 blacks against those of light complexion. The 

 more orderly of the Liberians would rejoice if 

 they could be relieved of the leader in this 

 course of mischief. 



An election for President took place on May 

 4th. The candidates were ex-President James 

 S. Payne, and the Vice-President, J. W. Gard- 

 ner. James Spriggs Payne was born in 1815, 

 in Virginia, and went to Liberia when about 

 ten years of age. He received a good education 

 in the mission-schools of Liberia, then under 

 the control of the Methodist Episcopal Church 

 of the United States. He became a minister 

 in that church, and enjoys the reputation of 

 being the most eloquent doctrinal preacher in 

 Liberia. He was President from 1868 to 1870. 

 Mr. Gardner was also born in Virginia, and 

 has been Vice-President four years. The elec- 

 tion resulted in the choice of Mr. Payne. 



LIGHTNING-RODS. In a valuable paper 

 on this subject, published in the Journal of 

 the American Electrical Society, Mr. G. N. 

 Miller points out certain grave defects in the 

 present methods of erecting rods, and how 

 these may best be remedied. As commonly 

 put up, lightning-rods are defective 1. In be- 

 ing insulated from the building ; 2. In the lack 

 of perfect joints where the sections come to- 

 gether ; 3. In failing to connect with the me- 

 tallic fittings of the building ; 4. In the charac- 

 ter of the ground-connection. The purpose of 

 the rod is to furnish an easier route for light- 

 ning to pass to the earth than that afforded by 

 the building. A good metallic conductor, such 

 as iron or copper, properly erected, practically 

 secures this without the costly refinements 



ordinarily attached. Regarding the polished 

 points which terminate the rod above, the 

 author gives good reasons for doubting their 

 value. If the rod provides an easier track to 

 the ground than the building, the lightning 

 will follow it, whether it passes a cluster of 

 fancy points or not, and if these really invite 

 the discharge from a passing cloud, when it 

 would not otherwise occur, that is a sufficient 

 reason for leaving them off, terminating the 

 rod in a single blunt point. As for insulators, 

 if the track made by the rod is not a perfect 

 one, they will not perceptibly hinder the pas- 

 sage of electricity into the building, a discharge 

 of such high tension as that from a thunder- 

 cloud penetrating an inch or two of glass with 

 the greatest ease ; while if the rod is a good 

 one there is no need of insulation, as the elec- 

 trical discharge never leaves an easy line of 

 transit to take a more difficult one. Concern- 

 ing the presence of joints in the rod the author 

 says: 



Some discussion has arisen as to the effect of 

 .joints in lightning-conductors, whether a riveted 

 joint best answers the purpose or a soldered one. 

 There is this difference between electricity of low 

 and electricity of high tension : tlie latter has a pe- 

 culiar power of overcoming resistances that the for- 

 mer does not possess. A current of low tension, for 

 instance, will pass over a telegraph-wire hundreds 

 of miles, and enter the earth in preference to leaping 

 across the shortest conceivable space of air to an 

 41 earth " in the immediate neighborhood, while a 

 current of high tension will often leap several feet 

 through the air to earth, in preference to following 

 the wires that are connected to the earth a few miles 

 distant. If we measure the conductivity of a joint 

 by employing a current of low tension ? and obtain 

 a certain result, as we increase this tension, the con- 

 ductivity of the joint also seems to increase, and 

 when the tension approximates that of a lightning- 

 discharge, the joint appears to offer little or no re- 

 sistance at all. If the joints are made in such a 

 manner as to prevent the different sections of the 

 rod from separating, that I think is all that is re- 

 quired. 



The object of connecting the rod with a 

 metallic roof, if such is present, gutters, con- 

 ductors, etc., is to relieve the building through 

 the rod of any electricity accumulated by in- 

 duction, and which might cause damage in its 

 passage to the earth if some easy outlet were 

 not provided. 



The ground connection, as usually made, is 

 totally inadequate, and vitiates every excel- 

 lence the rod may in other respects possess. 

 Concerning it Mr. Miller writes thus : 



The important point involved in the construction 

 of lightning-rods, and the one which in practice has 

 been so much, neglected, is that of proper earth-con- 

 nections. To illustrate a perfect joint between two 

 conductors unequal in size and conductivity, let us 

 take two rods, each one foot in length, one .copper 

 and the other iron, the latter having a sectional area 

 seven times as great as the former. Now, as copper 

 is about a seven times better conductor than iron, 

 these two rods would be equal as conductors, the 

 better conductivity of the copper compensating for 

 the increased size of the iron. Let us join these two 

 rods, forming a perfect joint. If the joint is per- 

 fect, the compound rod will be equal in conduc- 

 tivity to a copper rod two feet long, and of the same 



