^\ 





LEutered at the Posi-OlEcj of NewA'ork, N.Y., as Second-Class Matter.] 



A WEEKLY NEWSPAPER OF ALL THE ARTS AND SCIENCES. 



Eighth Year. 

 Vol. XYI. No. 406. 



NEW YORK, November 14, 1890. 



Single Copies, Ten Cents. 

 $3.50 Per Yeak, in Advance. 



LIGHTHOUSE ILLUMINANTS.' 

 It will be remembered that some years ago the Trinity 

 House appointed a committee to carry out experiments at 

 the South Foreland with a view of investigating the relative 

 advantages of oil, gas, and electricity as lighthouse illumi- 

 nants. Three experimental towers were erected, and were 

 appropriated respectively to electricity, to Mr. Wigham's gas 

 apparatus, and to oil, with occasional gaslighls. Each 

 lighting system was adapted to be shown in the multiform 

 arrangement; i.e., with lights placed vertically one above 

 the other. For gas, provision was made for showing four 

 lights, while the electric and oil systems had three lights 

 each. Observers were placed in huts at distances of 2,144 

 feet, 6,200 feet, and %\ miles. For observations at greater 

 distances, advantage was taken of the services of the coast- 

 guard between the North Foreland and Dover; of the light- 

 men on the "Gull," the "Goodwin," and the " Varne " 

 lightships; of the lighthouse-keeper at the North Foreland; 

 of pilots and masters navigating in the vicinity; and of the 

 Elder Brethren and their officers. More than six thousand 

 observations were taken. Tbe conclusions arrived at were, 

 (1) that the electric light was the most powerful under all con- 

 ditions ; (2) that the quadriform gas apparatus and the ti'iform 

 oil apparatus were of about the same power when seen 

 through revolving lenses, the gas being "a little better" 

 than the oil ; (3) that through fixed lenses the superiority of 

 the gaslight was unquestionable (the large size of the flames 

 and their nearness together gave the beam a more compact 

 appearance) ; (4) that the Douglass gas-burner was more 

 efficient than the Wigham burner; (5) that for the ordinary 

 necessities of lighthouse illumination mineral oil was the 

 most suitable and economical illuminant, and that for salient 

 headlands, important landfalls, and places where a very 

 powerful light was required, electricity offered the greatest 

 advantages. 



This report did not please the advocates of gas. Memori- 

 als were poured into the Board of Trade from ship-owners, 

 both individuals and associated bodies, asking that the ex- 

 periments might be continued with duplicated gas apparatus 

 of Wigham's pattern, this being undei-stood to give greatly 

 increased brilliancy. The board replied that they were in- 

 formed that these experiments would cost £18,000, in addi- 

 tion to the £9,000 already spent, and that the state of the 

 Mercantile Marine Fund would not allow of such an expen- 

 diture. Mr. Wigham characterized the estimate as "mon- 

 strous," and subsequently undertook to guarantee the ex- 

 pense should not exceed £2,000, if the existing apparatus 

 ' Prom Engineering of Got. 31. 



were used, and the services of the various employees given. 

 The Trinity House replied that a great deal of the apparatus 

 had been put into actual service elsewhere, and that Mr. 

 Wigham had ignored the expense of establishing multiform . 

 oil and electric lights in comparison with his multiform gas- 

 lights. 



Another objection brought against the report was that the 

 final conclusion of the Trinity House ignoring gas was not 

 justified by the record in the report itself. It was therefore 

 urged upon the board that the report should be remitted to 

 some independent scientific authority to determine if the 

 evidence bore out the conclusions. Eventually this course 

 was adopted, and the report sent to Sir George Stokes, presi- 

 dent of the Royal Society, who associated with himself Lord 

 Eayleigh and Sir William Thomson. These gentlemen have 

 now reported to the Board of Trade at very considerable 

 length, and, while their conclusions bear out to a large ex- 

 tent those arrived at by the Trinity House, yet they are dis- 

 tinctly more favorable to gas. They admit that it was quite 

 natural that the splendid lights erected on the Wigham sys- 

 tem on some parts of the Irish coast should have raised in 

 the minds of shipowners a feeling in their favor; but they 

 point out that the question at issue does not relate to what 

 has been done in the past, but that it is, " Does gas possess 

 such advantages over oil as to outweigh the greater sim- 

 plicity and economy of the latter illuminant, and should 

 both, in the case of lights of special importance, be aban- 

 doned in favor of electricity ? " 



The 108- jet gas burner gives a broader flame than the 6-wick 

 oil-burner; and with lenses of similar apertures and focal 

 lengths, and equal velocities of rotation, the diverging beam 

 from the gas is of longer duration. This has been taken 

 advantage of by Mr. Wigham for the introduction of a group 

 flashing system, by which it is sought to give each light a 

 distinctive character. The report states, however, that with 

 revolving lights the number of flashes in a group is some- 

 what uncertain; with fixed lights there is nosuch uncertainty. 

 The intermittence of a revolving light is obtained very 

 sharply and suddenly, by turning the gas completely out, 

 and by relighting it with a burst, resulting from allowing 

 the gas to flow for an appreciable time before the flame is 

 applied. With oil, intermittence can only be obtained by 

 means of shutters, as it is not feasible to turn the light out. 

 When the Wigham burner was compared with the Douglass 

 burner, it was found that the latter gave the more light for 

 a given consumption of gas. The smaller size of the flame 

 also augmented tlie brightness of the flash. The Douglass 

 burner, however, requires a glass chimney, which may give 



