JoLY 11, 1884.] 



KNOWLEDGE ♦ 



59 



practical mode of distributing light for a main street, like that of 

 Wimbledon, is by means of 50-candle lamps, fixed 20 ft. high, at 

 intervals of 100 ft. The effects were admitted to be remarkably 

 striking, and to furnish a capital example of efficient street light- 

 ing. We hear that it is within the range of probabilit)' that similar 

 experiments will, ere long, be tried in some of the busier City 

 thoroughfares where arc lights, although not a failure, have 

 apparently fallen short of their anticipated success. 



Electro-Magnktic Induction. — At the Physical Society recently 

 Mr. C. V. Boys exhibited the phenomenon first observed by Fara- 

 day, that a copper disc suspended bitilarly between the poles of an 

 electro-magnet, so as to cross the lines of magnetic force at an 

 angle, is suddenly kicked or twisted parallel with the lines of force 

 when the magnet is excited. If the disc be perpendicular to the 

 lines of force it is repelled by a pole when the magnet is made and 

 attracted by the same pole when the magnet is unmade. Mr. 

 Boys has investigated the phenomenon very fully, and points out 

 tliat it offers a quick and ready means of measuring the intensity 

 <rf an electro-magnetic tield, as well as a means of finding the 

 <?lectric resistance of plates and discs of metal. — Enginei'i-inrf. 



Mr. Charles Bati relor, who has been engaged in developing the 

 Edison system in Europe, states that the contracts on hand at the 

 factories on the Seine are more than the 400 employ^i can carry out 

 Hft present, ilr. Batchelor proceeds : — "The French company is com- 

 pleting a 20,000 light circuit for l*aris. It covers the very heart of 

 the city, the Kue de I'ttpera, and other points which have heretofore 

 been unsuccessfully attempted to be covered, by the best class of 

 :irc lights. The company has lighted already the Hotel dc Ville, 

 and has over G.OOO lights in the Grand Opera House, 2,000 in the 

 Kden Theatre, 1,200 in the Comique, 1,200 in the Vaudeville, and 

 1,200 in the Grand Hotel. Mr. Batchelor thinks it a fair estimate 

 to say that the contracts of the company now cover about 26,000 

 private lights to which no power is furnished, but only the globes, 

 <S:c. There are 600 lamps in La Nouveaute, 500 in La Variete, 500 

 in La Bouffe Parisenne. They are to be found in all the caft^!i front 

 the Sladeleine to the Variete, and as far north as the Gare St. 

 Lazare, and as far south as the Hotel Continental. Through all 

 this district, the most imjiortant in the city, the company has the 

 option of the right of way for all i>rivate lighting purposes on the 

 payment of two and a half million francs, and its rights are 

 guaranteed by the Government. 



At the meeting of the Geological Society, on June 25, the follow- 

 ing communication was read : — " Additional Notes on the Jurassic 

 Rocks which underlie London." By Professor John 'W. Judd, 

 F.R.S., Sec. G.S. Since the reading of the former paper on the 

 eubject (Feb. 6. 1881), the well-boring at Richmond has been 

 carried to a depth of more than 1,360 ft. The point reached is, 

 reckoning from Ordnance-datum line, 220 ft. lower than that 

 attained by any other boring in the London basin. A temporary 

 cessation of the work has permitted Mr. Collett Homersham 

 to make a more exact determination of the underground tem- 

 perature at Richmond. At a depth of 1,337 ft. from the surface, 

 this was found to be 75^° Fahr., corresponding to a rise of 

 temperature of 1° F. for every 5243 feet of descent. The bore is 

 still being carried on in the same red sandstones and " marls," ex- 

 liibiting much false-bedding, which were described in the previous 

 communication. The Rev. H. H. Winwood, of Bath, has had the 

 good fortune to find the original fossils obtained by the late Mr. C. 

 Moore from the oolitic limestone in the boring at Meus's Brewery 

 in 1878. A careful study of these proves that though less numerous 

 and in a far less perfect state of preservation than the fossils from 

 the RichmoTid well, they in many cases belong to the same species, 

 and demonstrate the Great Oolite age of the strata in which they 

 occtirred. 



The Destbuction of Wild Bikds in India. — Under the auspices 

 of the East India Association, a meeting of naturalists, planters, 

 sportsmen, and others interested in the affairs of India wes held on 

 Friday, July 11, at the rooms of the Zoological Society, under the 

 presidency of Professor Flower, LL.D., F.R.S. (Director of the 

 British Museum Natural History Department, and President of the 

 Zoological Society), for the purpose of urging the necessity of 

 Government measures for the preservation of wild birds in India. 

 The principal address was dehvered by Mr. Robert H. Elliot, some- 

 time planter of Mysore, and a well-known writer upon Indian topics. 

 He pointed out that every civilised Government, with the exception 

 of that of India, has recognised the value of birds as insect eaters, 

 and has adopted measures for their preservation ; and that the 

 absence of legislation forebodes, where it has not yet presented, 

 serious results to planters and agriculturists. As tlie most conve- 

 nient season for the destruction of birds is during the fine weather 

 that succeeds the heavy rains of the monsoons, and as this season 

 is also the breeding time, the destruction of insect-eatiug birds 

 proceeds at such a rate as must soon lead to almost absolute exter- 

 mination, unless preservative measures are speedily adopted. There 



was a general agreement in the meeting that legislation on the 

 subject is imperatively reqtiired, and it was resolved that a repre- 

 sentation to that effect should be addressed to the Government of 

 India. 



Birds Caught and Killed by the Electric Light. — A despatch 

 from Winona, Minn., describes a very curious incident in connec- 

 tion with the use of the electric light there. It says : — Every night 

 this week thousands of migratory birds have gathered about the 

 electric light on the stand-pipe in this city. Between the hours of 

 one and two o'clock the birds were seen in swarms about the light, 

 and hundreds fell to the ground. A few were caught alive, but the 

 larger part were dead. Prof. Holzinger, of the normal school, 

 reports the following species among those collected during the past 

 two nights at the waterworks: — Catbirds, grossbeaks in variety, 

 scarlet ranagers, golden crown thrushes, water thrushes, chestnnt- 

 sided warblers, blackburnian warblers, Tennessee warblers, magnolia 

 warblers, Carolina rails, yellow-throated vireos, black and white 

 creepers, traels, fly-catchers, green-crested fly-catchers, Savannah 

 sparrows, white-throated sparrows, Maryland yellon'-tbroats, black- 

 billed cuckoos, helldivers, indigo birds, and yellow-bellied wood- 

 peckers. On Tuesday night the grossbeaks predominated, and on 

 AVednesday night the rails. Catbirds were numerous on both 

 nights. The birds which breed in this locality were noticeably 

 absent. S'aluable additions from these birds are being made to the 

 museum of the Society of Arts and Science, and a set of duplicates 

 of most of the varieties has been furnished by Prof. Holzinger ta 

 the high school collection. Many of the birds which were caught 

 alive may be seen in cages at the engine-house of the waterworks. 

 — Electrical World (New York). 



It has been stated that the Times of June 14 is the largest pro- 

 duction that has ever issued from the daily press with the excep- 

 tion of the Times for Jane 21, 1861. We, therefore, have pleasure 

 in drawing attention to the following : — The Times issued June 14 

 consisted of twenty-four pages, each containing six columns — 144 

 columns in all; the total length of which was 264 feet — 52 feet 

 higher than the monument; and they contained enough matter to 

 fill two volumes of 480 pages. Almost every week, at least one 

 issue of the Daily Detroit Free Press consists of twenty-four pages 

 of seven columns each. On June 2, 1878, it consisted of thirty-two 

 pages of seven columns each. On June 8 this year, in cele- 

 bration of its removal into the new Free Press Building, 

 Detroit, and on or about its fifty-third birthday, The Daily 

 Detroit Free Press consisted of thirty-six pages of seven 

 columns each — the largest paper ever printed in the world, 

 we believe. This gives 252 columns, whose total length is 420 feet 

 — double the height of the Monument, and sixteen feet to spare. 

 The paper used to print this edition, run off the reels in a straight 

 line, would extend 108 miles ; while, spread out wide, it would, 

 cover 25 acres ; piled sheet on sheet, as folded, it would tower up 

 nearly three times the height of the Monument ; and, in book form, 

 it would fill two volumes of 600 pages each. The mechanical work 

 — composing, stereotyping, and printing — occupied 148 men ; and 

 the literary matter, outside the reports of the Associated Press, 

 was furnished by no less than thirty-five editors, reporters, and 

 regular contributors attached to The Free Press staff, and forty-two 

 correspondents in various parts of the world. The price was five 

 cents, aa usual. 



Colouk-Blixdness. — There is every reason to believe that the 

 new apparatus for combining colours, devised by Mr. Offert and by 

 Lord I?ayleigh, will lead to a thoroughly scientific investigation of 

 colour-blindness. Considering how common Daltonism is, and how 

 essential it is that railway men and others working with coloured 

 signals should be free from it, or at least know the extent to which 

 they suffer from it, some simple means of investigating it is desirable. 

 Lord Rayleigh's apparatus is based on double refraction, and the 

 obtaining of two overlapping spectra, which the person under 

 examination looks at, and describes as green, blue, or purple, what- 

 ever it appears to his or her sight. Lord Rayleigh has, we believe, 

 tested the vision of numerous friends, and is willing to extend his 

 observations further. So far he has found that the majority of 

 persons tried require only half as much red in the mixed spectra to 

 turn a given yellow into green as he himself does. People vary from 

 each other in matching colours, and there are grades of " colour- 

 blindness." Ordinary colour-blindness is blindness to red, but the 

 father of Mr. Stanley, the optician, was colour-blind to green. As 

 an engineer, when engaged in colouring plans, he had to single out 

 his green pigments by their names. To him they appeared a 

 kind of brown. Lord Rayleigh has not, we understand, noticed 

 any striking differences between the two eyes of the same person, 

 except what is due to fatigue of one eye and freshness of the 

 other. Dr. Guthrie, who is colour-blind to red, believes himself 

 more than usually sensitive to blue ; and Lord Rayleigh has found 

 persons abnormally sensitive to red, as well as abnormally insen- 

 sitive to it. It would be interesting to discover whether such 



