120 



SCIENCE. 



[Vol. XII. No. 292 



Red, etc., — which have a steep declivity, but flow in broad, shal- 

 low valleys, are examples. 



This matter is fully discussed by Powell in the report above 

 cited (1876), and by Gilbert in his report on the Henry Mountains 

 (1880). Russell Hinman. 



Cincinnati, O., Aug. 27. 



[Our esteemed correspondent misapprehends the scope and 

 specific limitations of this " new law in the hydraulics of rivers," as 

 he also does those of the law announced by Major Powell in his 

 report on the Uinta Mountains, in 1876. In neither case is the 

 law stated as a general one. Major Powell has never said, and does 

 not now say, that in all rivers, and under all circumstances, " cor- 

 rasion of every kind is increased by increase of load," although it 

 may be true. But that is what our correspondent seems to sup- 

 pose Major Powell's law of 1876 meant. Stated in its simplest 

 form, the law of 1876 is as follows : "In a region of degradation, 

 Tjerlieal corrasion is increased by increase of load, in a diminish- 

 ing ratio!' He never dreamed at that time that this law could be 

 generalized, or even that any similar law would explain lateral cor- 

 rasion by a river flowing through a flood-plain. The new law 

 which he now proposes as the result of subsequent study is, "In a 

 region of sedimentation [and it must be noted that the flood-plain 

 of the Mississippi is a delta region, and therefore a region of sedi- 

 mentation] an increase of load increases lateral corrasion iji a 

 e;eometric ratio!' We did not emphasize this distinction in the 

 brief editorial reference which we made to Major Powell's paper, 

 assuming that any reader who had given especial attention to the 

 study of the hydraulics of rivers would make it for himself, cer- 

 tainly if he read Major Powell's paper printed in the same number of 

 Science, and beginning on the same page with the editorial para- 

 graph referring to it ; for all others the law was stated in the least 

 confusing, although perhaps not in the most comprehensive lan- 

 guage. — Ed.] 



A Notable Evolution. 



The remarkable power of the catbird as a singer is known to all 

 those who give it a safe and welcome retreat. Yet I find even such 

 writers as Baird describing it after this manner : " An American 

 bird of the thrush family, whose cry resembles the mewing of a 

 cat." In reality it is the mocking-bird of the Norlh, possessed of 

 ability to sing whatever notes he hears. I have them so perfectly 

 at home in my grounds, that their delicious music is heard at all 

 hours of the day, and often in the middle of the night. It is very 

 curious to hear one of them warble in a low key to himself what 

 some other bird is singing loudly. A few days since I heard one 

 mimic a red squirrel, and he did it to perfection. If he had not en- 

 joyed the fun so well that he could not keep from hopping about, I 

 should not have known which was squirrel. 



I did not, however, intend, except incidentally, to write about the 

 catbird, Minms Carolinetisis. It, however, makes it easier for us 

 to conceive the possibility of an evolution of superior vocalization 

 in his relatives, when we consider his masterly ability. What I 

 wish to record is a remarkable development in the case of his cousin 

 the common robin, or migratory thrush. Every one knows what a 

 clumsy singer he is, having a rough, see-saw note, that he repeats 

 with little variation. For some reason the other birds give him 

 precedence in the morning song with which daylight is greeted 

 about half-past three in June. The first note comes always from 

 the east, — a faint, far-away cry; then another cry leaps out of a 

 tree nearer you, and then another and another. So the wave of 

 robin-melody moves westward, over the house and over the land, 

 preceding the rising sun, probably from the Atlantic to the Pacific. 

 This song is peculiarly adapted to constitute a matin cry, being 

 clear, strong, and cordial. But it is not musical. In June of 1887, 

 crossing one of my lawns, I heard a cry so peculiarly like articula- 

 tion that I was startled : " Hear this birdie ! Hear this birdie ! 

 Hear this pretty birdie ! " the last notes being exquisitely rendered, 

 with a wave and upward bend. I had never heard such a song 

 before, and imagined a new species of bird must have arrived ; but 

 after careful examination, I found the singer to be a veritable robin- 

 edbreast, and not a new-comer at all. The song was repeated all 



the summer, to the delight of myself and friends. Of course, I 

 awaited the opening of spring with anxiety, to know if our birdie 

 would return. Almost the first song of spring, sure enough, was 

 one morning in April : ■' Hear this birdie ! Hear this birdie ! " 

 But, better yet, it was apparent that the babes of this family were 

 singing, not the old robin's see-saw, but the new song. And now 

 about my place are three or four of our birdies. What was notable 

 was not only the remarkable evolution of musical power, but a love 

 for music ; for our birdie, unlike the robins in general, sang all 

 day, like the catbirds. I could hear one or more at almost any 

 hour. This drew my attention to the cause of the unexpected 

 variation. John Burroughs suggested that it might be the song 

 taught to one that had been caged and afterwards escaped ; but I 

 am more inclined to think that it is a natural variation or evolution, 

 and that the robin has great and undeveloped power. It is a phleg- 

 matic bird, that takes the world easy, and is not likely to exert itself 

 in new directions. The catbird is fond of notice, likes to be whis- 

 tled to, and enjoys answering back. He is likely to develop all 

 sorts of new vocal accomplishments. But the robin is really lazy, 

 and does as little hard work as possible. His nest is a clumsy 

 affair, a mere daub of mud and sticks. Why has he begun this 

 new song ? Is it from being so constantly with catbirds, gross- 

 beaks, orioles, etc. ? for my nine acres are the paradise of birds. 

 They are covered with fruits, hedges, trees. I do not know, but 

 believe, some such cause to be at the bottom of the affair, and that 

 we may look for other developments quite as remarkable. Within, 

 the month of June, whfle driving about five miles from my home, I 

 saw a robin sitting on a wayside fence, and singing a set of notes 

 most charmingly unlike any thing I had ever heard ; neither was it 

 at all like our birdie. It was as complex as a catbird often sings,, 

 but not apparently imitative. This has led me to a very decided 

 conviction that an evolution in robin-music is now going on, and 

 that some very delightful results may be looked for. I shall be glad 

 to get notes from observers in different parts of the country. Of 

 this I am certain, that our common thrush has a vast vocal power 

 undeveloped. Evolution with birds must move, as it has moved, 

 in the line of music, plumage, and flight, and nest-building. Noth- 

 ing in these directions need surprise us. 



I subjoin a note taken from a paper published near New York 

 City, over two hundred miles from here: "Thomas O'Donnell of 

 Rondout has a robin which whistles like a mocking-bird. This is 

 probably due to the fact ttiat it was raised in company with a 

 mocker. The robin whistles ' Johnny, get your Gun," and ' Don't 

 leave your Mother, Tom ! ' Its powers of mimicry are wonderful. 

 In the early morning, when things are quiet, the whistle of the bird 

 has l)een heard a quarter of a mile. One day recently a man went 

 into a saloon over the door of which the robin hung. The bird 

 gave a sharp, quick whistle,. which a man across the way, seeing his 

 friend enter the saloon, considered a call to get a free drink. The 

 man who first entered the saloon denied having whistled, but he 

 nevertheless stood treat." I am confirmed by such reports in the 

 belief that we shall see a remarkable evolution of robin-music. 

 Our homestead pet and universal favorite will then be all the more 

 dear. E. P. Powell. 



Clinton, N.y., Aug. 28. 



Queries. 

 36. Double Fruit. —- Last May a gentleman brought into my 

 office a peach-tree branch quite thickly covered with small green 

 peaches, most of which were double ; that is, consisted of two (in 

 several cases three) peaches, more or less completely fused into 

 one. Some of the members of these doublets were hardly dis- 

 tinguishable as such, except by the fact that they had two stones ; 

 while others were scarcely united, and a few were entirely dis- 

 tinct from each other, but had only a single stem. Later I learned 

 of such peaches being common in two other widely separated 

 localities in this State this year, but no one had ever seen them 

 in any previous year. I have also a collection of ripe cherries 

 doubled in a similar way, and gathered this year from a tree in 

 this city. Is this a common phenomenon ? What is the appear- 

 ance of the flower which gives rise to this double fruit ? J. L. H. 



Louisville, Ky., Aug. 7. 



