332 



SCIENCE. 



[Vol. VII., No. 166 



left. Nothing more was seen of them till after 

 the author's return from his summer vacation, in 

 the middle of September, when a single female of 

 this species made its appearance. In their inability 

 to obtain an entrance through the closed window, 

 they had evidently built a new nest in the vicin- 

 ity, and reared their broods. 



These circumstances indicate that the intel- 

 lectual powers of the humble-bee are not as slight 

 as we have been accustomed to believe. Here in 

 this case, from October to April, — a period of six 

 months, — had these bees remained dormant in 

 the ground, or hidden in some crevice, and, upon 

 regaining their activity, had not only remembered 

 the place where they were, but had sought and 

 found, despite the many difficulties, their last 

 year's nest. That these individuals were from the 

 previous year's brood, there was no doubt, as 

 throughout the province the species nowhere else 

 occurs, peculiar as it is to elevated and mountain- 

 ous regions. 



LIGHTHOUSE ILL UMINANTS. 



At the meeting of the London society of arts 

 held on March 10, Mr. E. Price Edwards read a 

 report of the experiments on lighthouse illu- 

 minants made at South Foreland during 1884- 

 85. The experiments show that in clear weather 

 all the lights — electric, gas, or oil — were too 

 good, and that for merely sending an effective 

 beam of light to the horizon on a dark, clear 

 night, no one was really better than the other, 

 although it should be said that the electric light 

 used, on account of its dazzling brilliancy, was 

 regarded as a nuisance rather than otherwise by 

 mariners in the near neighborhood of South Fore- 

 land. It is quite certain that for clear weather 

 the lower powers of any one of the illuminants 

 would be sufficiently serviceable for the require- 

 ments of the mariner. 



The oil and gas lamps were rendered thus 

 effective by superposing one upon another series 

 of flames. It was found, that, in respect to the 

 adaptability of the lights for occupations,— one of 

 the distinctive characteristics used for lighthouses, 

 — gas was especially available, as by simply turn- 

 ing off the supply an occultation is promptly pro- 

 duced in an economic and an effective manner ; 

 whereas, with the electric or oil lamp, the use of 

 a revolving screen was found most suitable. For 

 colored sectors, on the other hand, the electric 

 light is most serviceable, as, on account of its 

 small surface, the change in color may be made 

 more abruptly. 



The general results of the observations in hazy 

 weather show incontestable' that a single electric 



light greatly excels the most powerful oil or gas 

 light in penetrating-power. In an actual fog the 

 electric also holds its own. The experience of 

 fogs at South Foreland was not large, but was 

 sufficient to furnish available comparisons ; and it 

 was proved beyond question that the single elec- 

 tric light pierces a greater depth of fog than the 

 highest power available of either gas or oil, but 

 in heavy fogs the mariner would not derive the 

 slightest advantage from any of the lights used. 

 The recorded distances to which lights were car- 

 ried, or where they were picked up, in heavy 

 fogs, range mostly from seven hundred to two 

 thousand feet ; and the superiority of the electric 

 light is determined by penetrating two hundred 

 or three hundred feet farther than the gas or oil 

 light. The most powerful electric light was shut 

 out on one occasion at fourteen hundred and fifty 

 feet, on another at fifteen hundred, another at 

 seventeen hundred, another at fifteen hundred, and 

 another at thirteen hundred feet. It will be plain 

 to all that no mariner could be benefited by a 

 light which was not visible at such distances from 

 the lighthouse ; and, for the purpose of navigation, 

 a difference in the visibility of the lights of two 

 or three hundred feet is of no value whatever. 



One fact stands out prominently ; viz., the 

 greater ratio of absorption by the fog of the elec- 

 tric rays as compared with that of the gas or oil 

 rays. Fortunately for the electric light, as shown 

 at South Foreland, it possesses a large reserve of 

 initial intensity, which enables it, notwithstand- 

 ing its much greater proportion of loss by absorp- 

 tion of its more refrangible rays, to penetrate 

 farther than the other luminants. With three 

 lights of equal candle-power, — one electric, one 

 gas, one oil, — exhibited in a foggy atmosphere, 

 there is little doubt that the electric will be 

 eclipsed at a much shorter distance than the 

 others. But as an electric beam can be made 

 so much more intense than it is possible to make 

 the gas or oil beam, the electric light, though 

 heavily handicapped by its competitors, by the 

 very superabundance of its own luminous energy, 

 may be made to penetrate the farther. 



The experiments have also shown clearly that 

 the lights from gas and oil are very much alike 

 in illumining-power : indeed, under some condi- 

 tions, the oil-flames seem to be rather the better. 

 They have also shown that the oil-lights can be 

 superposed with the same facility as the gas- 

 lights. As yet, no oil-flame has been brought to 

 the enormous size of the 108-jet burner ; but, as 

 this enormous size of flame is not required, the 

 difficulty is of no great consequence. As the two 

 lights were shown to be so nearly equal, the 

 questions of convenience and economy assume 



