P OP ULAR MIS CELL ANY. 



285 



electrical conductors is avoided, and that the 

 capital invested is smaller than is required 

 for gas-works. Heretofore the difficulty ex- 

 perienced by electricians has been to divide 

 the light without weakening in too large a 

 degree its power. Should the system of 

 Messrs. Molera and Cebrian prove a practical 

 success, it may be economically used in light- 

 ing not only private residences and public 

 institutions, but even whole cities." 



Color-Bllndncss of Seamen. — An article 

 on color-blindness, in a lute number of 

 the " English Mechanic," quotes some very 

 important facts from the records of the 

 British Board of Trade, derived from exam- 

 inations of seamen applying for " mate's " 

 or " master's " certificates, concerning their 

 ability to distinguish colors. We select 

 a few from the many instances of color- 

 blindness detected by these examinations. 

 One seaman, a candidate for a second mas- 

 ter's certificate, described green glass as 

 " dark red " ; in another case a green card 

 was called " yellow " ; and a man who had 

 been over eighteen years at sea was report- 

 ed as quite unable to distinguish any of the 

 colors. Another who had been more than 

 seven years at sea described the red glass 

 by daylight as " green," the dark green as 

 "red," and the yellow as " red" ; while by 

 gaslight he named the light blue "green," 

 the dark green " red," and the yellow " red." 

 This appears to be a case of Daltonism, or 

 incapability of perceiving the red end of the 

 spectrum. There are several similar in- 

 stances which differ only in details ; but per- 

 haps the most interesting case is that of 

 a candidate for a second mate's certificate 

 who had served nearly five years at sea — a 

 case that ought to have been sent to a court 

 of appeal. By daylight he described the 

 red card as " green," the yellow and green 

 glasses " red," and the red glass as " dark 

 green." By artificial light he called the 

 yellow and green glasses "red," and the 

 white glass " dark green." This man ob- 

 tained a certificate from the London Oph- 

 thalmic Hospital testifying that he was not 

 color-blind, but on reexamination he still 

 described dark green as " red," light green 

 as "neutral," and yellow as "red" by arti- 

 ficial light, while by daylight he called the 

 green glasses "red" once and" yellow" 

 once. This last difference may have been 



caused by the manner in which the ques- 

 tion was put, and ignorance of the names 

 of colors. In view of these facts, the query 

 suggests itself, may not the recent dreadful 

 accident to the steamer Champion have been 

 due to the inability of the lookout to distin- 

 guish the Hghts on the other ship, which 

 was discovered only when near enough to 

 take in her general outline ? 



Apprentice-Schools in France. — This is 

 the title of a highly suggestive paper on 

 the subject of science teaching in the pub- 

 lic schools, read by Professor S. P. Thomp- 

 son at the last meeting of the British As- 

 sociation. As the subject is daily acquiring 

 new importance in this country, we present 

 a pretty full abstract of the paper as it ap- 

 peared in "Nature." The problem to be 

 solved, in the author's opinion, is, how to 

 give that technical training and scientific 

 knowledge to artisan children which their 

 occupation demanded, without detaining 

 them so long at their schooling as to create 

 a distaste for manual labor. There were 

 four solutions of the problem, all of which 

 had been tried, and illustrations of which 

 could be seen in Paris. They were : 1. Send 

 the children to work in the factory or work- 

 shop at an earlier age, making it obligatory 

 all through their apprenticeship that they 

 should have every day a certain number of 

 hours' schooling in a school in the work- 

 shop or attached to it ; 2. Keep the chil- 

 dren at school as long as their education 

 was unfinished, but set up a workshop in 

 the school, where they should pass a certain 

 amount of time every day so as to gain at 

 least an aptitude for manual labor; 3. 

 Organize a school and a workshop side by 

 side and coordinate the hours given to study 

 with an equal number of hours devoted to 

 systematic manual labor ; and, 4. Send the 

 children half the day to the existing schools, 

 and the other half to work half-time in the 

 workshop or factory. Schools of the first 

 type had existed in France for nearly thirty 

 years, and at the close of 1878 there were 

 no fewer than 237 schools of this character. 

 So far as he was aware, there was only one 

 school of the second type — the Ecole com- 

 munale d'Apprentis, in the Rue Touruefort, 

 Paris. The peculiarity of this school was 

 that workshop training was being given to 

 lads who had not yet completed a course 



