140 



POPULAR SCIENCE NEWS. 



[September, 1888. 



Saturn is a morning star rising at 2 a.m. at the 

 end of the month. It is moving out of Cancer 

 and into Leo toward the brightest star of the con- 

 stellation Regulus {Alpha Leonis). On Sept. 30 

 it is about 10° west of this star. Uranus is still 

 an evening star, but is rapidly nearing conjunction 

 with the Sun, and sets too early to be easily seen. 

 Neptune is south of the Pleiades, and rises a little 

 before midnight. 



The Constellations. — The positions given hold 

 good for latitudes differing not much from 40° 

 north, and for 10, 9, and 8 p.m. for the beginning, 

 middle, and end of the month respectively. 



Cygnus is directly overhead. Delphinus, high 

 up, and Capricornus, low down, are on the southern 

 meridian. Piscis Australis is below Capricornus, 

 and not quite up to the meridian. Aquarius is to 

 the left of Capricornus at about the same altitude. 

 After Aquarius come Pisces and Aries, the latter 

 being almost due east at about 10° altitude. 

 Taurus is just rising a little north of east. Pega- 

 sus is between Pisces and the zenith; and Andro- 

 meda is above, and a little to the north of Aries. 

 Cassiopeia is to the right, and a little above the pole 

 star. Perseus is low down to the north-east, and 

 Auriga is just rising below it. Draco is to the 

 west of the meridian. Ursa Minor mainly to 

 west of pole star at about the same altitude. 

 •Ursa Major is below the pole, a little to the left. 

 Lyra is just to the west of the zenith, with Hercules, 

 Corona Borealis, and Bootes below it, the last 

 being near the horizon a little north of west. 

 Scorpius is setting in the south-west, with Ophiu- 

 chus above it. Sagittarius is low down in the 

 south, a little west of the meridian; and Aquila is 

 high up between Sagittarius and Cygnus. 



M. 



Princeton, N.J., July 2, 1888. 



CorresponJitnte. 



Brief communications upon subjectn of scientific interest 

 Witt be welcomed from any quarter. The editors do not neces- 

 sarily indorse alt views and statements presented by their cor- 

 respondents. 



HOW BIRDS LEARN TO SING. 

 Sir: — 



Two of your correspondents in your July issue 

 dispiite my assertion that " young birds will never 

 sing the song peculiar to their tribe if they have 

 never heard it," and give instances to prove the 

 contrary. I cannot dispute the facts they adduce; 

 and if it be true that they have reared birds which 

 never heard the song of their tribe, and yet sing it, 

 my assertion must certainly be qualified, though 

 I do not accept their conclusion that birds sing by 

 instinct only, and not by imitation. My assertion 

 was given on good authority, that of such men as 

 the Hon. Dames Barrington (Philosophical Trans- 

 actions for 1773, vol. 63), and a later authority, 

 Alfred Russell Wallace, the well-known English 

 scientist, and the author, equally with Darwin, of 

 the theory of natural selection. Facts are given 

 the very opposite of those which your correspond- 

 ents allege to have come under their own observa- 

 tion. I accept both classes of facts, and conclude 

 that birds, like men, differ in|their physical and men- 

 tal powers, and also in the strength of their inherited 

 tendencies. Some birds evidently will not learn the 

 song of their tribe unless they hear it, and some 

 will. Man talks instinctively. Birds sing in- 

 stinctively. Man talks a particular language or 

 dialect by imitation, not by instinct. Birds learn 

 the song of their tribe by imitation, not merely by 

 instinct. That some birds sing the peculiar song 

 of their tribe without ever having heard it, as is 

 asserted, may probably be explained in this man- 

 ner: Most animals have a natural voice, which is 



determined by the form and physical qualities of 

 the larynx. Man talks, birds sing, dogs bark, 

 ducks quack. But birds and men possess more 

 varied vocal powers and greater power of imitation 

 than either dogs or ducks. Man talks, but may 

 talk English or French. The linnet sings, but may 

 sing the song of the lark, or the canary, if it hears 

 one of those, and not its own. A bird reared with 

 no opportunity of hearing the parent's song has the 

 instinct for singing. The form of its larynx, and 

 its inherited qualities, physical and mental, render 

 the parent's song the easiest; as they have rendered 

 that song the easiest, and therefore what is called 

 the natural song, for the tribe. It therefore sings 

 the song it has never heard. In other cases, as my 

 authorities testify, birds do not sing the song of 

 their tribe if they have never heard it. This 

 explanation agrees with both classes of facts. 

 Whether it is correct or not, I accept the facts 

 stated by your correspondents, but I entirely dis- 

 sent from their arguments and conclusions. The 

 idea that " there can be no similarity between a 

 bird and a man," that the bird is entirely governed 

 by instinct, and man by reason, is an old super- 

 stition without the slightest foundation in reason 

 or science. It is a distinction which science does 

 not recognize: it belongs to theology, where it 

 originated. The assumption of an essential dis- 

 tinction between reason and instinct applied to 

 the actions of birds and men, is as unscientific and 

 as untrue as the illustration of your correspondent 

 which is intended to support it, — " no more than 

 meteoric stars establish the course of the planets." 

 Well, they establish the course of the planets, if 

 by those words it is meant that their courses are de- 

 termined by the same causes, and their curves are 

 of the same character. Exactly the same forces 

 and the same laws which determine the course of a 

 meteor, determine the course of a planet. In either 

 case the curve described must be one of the conic 

 sections: it may be a parabola, hyperbola, circle, 

 or ellipse. The imagined distinction is unreal, like 

 that between instinct in animals, and reason in 

 man, which is an assumption unsupported by 

 evidence, and unrecognized by science. I adhere to 

 the opinion that the singing of birds, like the talk- 

 ing of men, is the result, partly from instinct, 

 and partly from imitation. 



Yours faithfully, 



Sam'l Brazier. 

 No. 6 Allston Place, Boston. 



OPTICAL ILLUSIONS. 

 Editor Popular ScIE^•CE News: 



I WAS interested in the optical illusions illus- 

 trated on pages 97 and 98 of your July number. 

 Like you, I cannot look at them without seeing 

 them constantly in motion; in fact, they impress 

 me as being alive. I wish to call attention to 

 another illusion connected with these figures, which 

 I have never seen mentioned, but which is very 

 curious. 



When either Fig. 2 or Fig. 3 on page 98 are rotated 

 rapidly, with the rinsing movement you describe, 

 there appears, within each party-colored circle, a 

 smaller circle of just half its diameter, rolling 

 round its inner circumference, and of a plain slate 

 color, evidently a combination of the black and 

 white divisions. When these segments or divis- 

 ions are alternately blue and yellow, instead of 

 black and white, the resulting inner circle is green; 

 and so with other colors, the inner circle is a com- 

 bination of the two. The general explanation of 

 these illusions, I suppose, must be in the fact that 

 impressions on the retina continue for a brief 

 space after the object is removed; but to show 



exactly how these appearances are produced upon 

 that principle, would be difiicult indeed. 

 Very truly yours, 



J. P. Apthorp. 



Tallahassee, Fla., July 30, 1888. 



QUESTIONS AND ANSWERS. 



Letters of inquiry should enclose a two-cent stamp, 

 as well as the name and address of the writer, which 

 will not be published. 



Questions regarding tlie treatment of diseases can- 

 not be answered in this column. 



. W. M. I., New Fojfc. — What can be added to a 

 solution of nitrate of silver to prevent its staining the 

 fingers, and decrease its sensitiveness to liglit? 



Ansi"er. — You can do nothing to prevent nitrate of 

 silver from staining the fingers, except to keep it away 

 from them. Tlie stains can be removed by hyposul- 

 phite of soda. Some photographers use the more 

 effective cyanide of potassium, but we would not rec- 

 ommend the use of this extremely poisonous sub- 

 stance. 



It is a mistaken idea that pure nitrate of silver is 

 affected by light. Such is the case only when organic 

 matter or other impurities are present. Take a solu- 

 tion of nitrate of silver, and expose it to strong sun- 

 light. It will become black and turbid, but in a short 

 time will clear up, and deposit a black powder which 

 is principally metallic silver. The organic matter has 

 been oxidized at the expense of the oxygen in the 

 nitrate. The chloride, bromide, and iodide of silver 

 are affected by light, and these are the salts used in 

 photography. 



H. & W., New York. — Has the electric light any 

 bleaching effect upon colors? and, if so, is the arc, or 

 incandescent, liglit more powerful ? 



Ajiswer. — We do not think that either form of light 

 would have any appreciable effect. The arc-light is 

 richer in actinic or chemical rays than the incandes- 

 cent, but probably either kind could be used with 

 safety. 



H. W. B., Chicai/o. — Why is aluminium so hard to 

 reduce the metallic state? 



Answer. — It is impossible to give a satisfactory 

 reason. It is one of the inherent properties of the 

 element; but why it is so, no one can say. Iron is an 

 element closely resembling aluminium in its chemical 

 relations; but, while its oxide is reduced to a metal by 

 simply heating with carbon, the most powerful redu- 

 cing agents are necessary to separate the oxygen 

 after it has combined with aluminium. Were it not 

 for this strong affinity between oxygen and aluminium, 

 that metal would be as cheap as, or even cheaper 

 than, iron. 



— »— 



LITERARY NOTES. 



Elementary Physiography. An Introduction to the 

 Study of Nature. IJy John Thornton Mack. 



Sound, Light, and Heat. By Mark R. Wright. 



These two works are published by Messrs. Long- 

 mans, Green & Co., New York and London, at eighty 

 cents each. They are written in a popular and easily 

 understood style, and are equally valuable, either as 

 an elementary introduction to a course of scientific 

 study, or for general reading. The volume on Physi- 

 ography treats of the structure of the earth and the 

 laws and action of the various geological and meteoro- 

 logical forces which act upon it ; wliile the one on 

 Sound, IJght, and Heat gives a remarkably good and 

 complete expo.sition of the phenomena and laws relat- 

 ing to those departments of pliysical science. The 

 books are fully illustrated, and, at the low price at 

 which they are published, ought to find many readers. 



The Octroi at lesoire, by David Starr Jordan, president 

 of the University of Indiana, is publislied in the 

 August number of the Popnlar Science Monthly of 

 New York. It is a remarkably brilliant satire, 

 and, although written for the purpose of exposiiig 

 the fallacies of the principles of a protective tariff, 

 will be read with interest and profit by protection- 

 ists as well as free traders. We have rarely seen 

 so good an argument for unrestricted commerce. 



Pamphlets, etc., received : Descriptive List of Works 

 on Civil Government, by the Massachusetts Society for 

 promoting Good Citizenship (Boston) ; International 

 Copyright on Works of Art, by Thomas Humpliry 

 Ward; Some lietrospertivc and Prospective Thovghts on 

 Surgery, by Donald McLean, M.D., of Detroit; Anti- 

 pyrine, by Benjamin Marshall, M.D.of San Francisco; 

 Report of the Managers of the Yale Observatory and the 

 Bulletins of the Experiment Stations of Louisiana and 

 Connecticut. 



