April 17, 1884] 



NA TURE 



573 



the assistance of C. K. von Baer and H. Kathke, and in the 

 second edition, 1S35, with the same assistance, and, besides 

 them, with E. Meyer and J. Valentin, and in a French transla- 

 tion of the same work, § 237 gives an account of Sprengel's dis- 

 coveries. " If he should have gone a little too far in some cases 

 it would be without importance ; the same occurs with every 

 scientist who makes a great discovei-y, and becomes with it 

 enthusiastically excited." I know personally that Burdach's 

 well-reputed assistantswere thoroughly acquainted with. Sprengel's 

 observations. 



Prof. H. Burmeister had studied in Greifswald and in Halle, 

 and published his " Handbuch der Entomologie," 1832 ; an 

 English translation by F. Shuckard. He speaks {vol. i. p. 303) 

 about Sprengel's and Koelreuter's observations at some length, 

 also as well known and of the highest importance. Prof. Bur- 

 meister will be indeed best able to state if he became acquainted 

 with the facts in Prof. Hornschuck's lecture on the physiology of 

 the plants, ' ' natur?e mysterias nobis aperire expertus est " ( " vita " 

 in Prof. Burmeister's dissertation), or in Halle by Prof. Carl 

 Sprengel, the nephew of Rector Sprengel, or somewhere else. I 

 know personally that in Berlin, Link, Lichtenstein, Klug, 

 Erichson were entirely acquainted with Sprengel's discoveries. 

 Prof. Kunth was a very old friend of Heim (Life, ii. p. 9), and 

 beyond doubt acquainted with the /acts, though he has not 

 brought it forward in his lectures after Dr. F. Miiller's state- 

 ment. I was assured by scientific friends that Treviranus in 

 Bonn and Nees von Esenbeck in Breslau were well acquainted 

 with Sprengel. I confess that I am entirely at a loss to under- 

 stand how it happened that Sprengel was unknown to scientists 

 in England, where Kirby and Spences '* Introduction," &c., 

 had seven editions from 1S15 to 1S67, the last of 13,000 copies. 

 There would be no difficulty to find in German libraries more 

 publications to corroborate my views, but I believe those quoted 

 are sufficient to prove what I intended to state in my former 

 note. H. A. Hage.n" 



Cambridge, Mass., March 24 



Salt-water Fish-Types in Fresh Water 



Mr. Hardm.'\.n's observations on the occurrence of " sea-fish 

 in fresh-water rivers" (N.4TURE, vol. xxix. pp. 452-53) are not 

 by any means unique, as he has supposed. On the contrary, 

 cases similar to those he has recorded are so frequent as to justify 

 him in belie\ing that "some caution must be observed in the 

 classification of strata as fresh-water or marine on the evidence 

 offish alone.'' The incursion and confinen.ent of the two types 

 specially mentioned — the "sunfish" and "shark" — in fresh 

 water have many parallels. For instance, in Nature, vol. xiii. 

 p. 107, Messrs. W. AV. Wood and A. B. Meyer have recorded 

 that " near Manila is the Lacuna de Baij, a large sheet of 

 water" whose "water is quite fresh, and, after settling, per- 

 fectly potable," but in which live a sunfish {Prbtis ptrotellii) and 

 a small shark. Further, in Lake Nicaragua, whose mean height 

 above mean tide in the Pacific and Atlantic Oceans is 107 '63 

 feet, are likewise found a sunfish — apparently Pristis antiquorum 

 — and a peculiar shark — Eulatnia (or Carcharias] nuaragtunsis. 

 The last have been especially noticed in a " Synopsis of the 

 Fishes of Lake Nicaragua, by Theodore Gill, M.D., andj. F. 

 Bransford, M.D., U.S.N. ," in 1877 (Proc. Acad. Nat. Sd. 

 Phila., pp. 175-91). Therein it is also urged that "these 

 instances, supplemented as they are by many others, are 

 sufficient to convey a caution against too extensive generalisation 

 of the physiographical conditions hinted at by fossil remains ol 

 aquatic types." Theo. Gill 



Washington, .April I 



"The Axioms of Geometry" 

 Mr. Robt. B. Hayward has written to me that some of the 

 statements in my article, "The Axioms of Geometry," in Nature, 

 March 13 (p. 453), are too sweeping, and that in particular 

 Euclid I. 16 does not necessarily hold for the geometry of the 

 eye-being, or, to use the more familiar language of spherical 

 geometry, that this theorem does not hold unless the median line 

 of the triangle on the side on which the exterior angle lies is less 

 than a quadrant. 



Mr. Hayward has also pointed out that the error lies in tlie 

 assumption that a terminated straight line " may be produced to 

 any length." 



All this is clear enough, and I was conscious of it when I 



wrote the article. In fact I meant to add, but somehow omitted 

 to do so, that every figure considered lias to be limited to less 

 than a hemisphere, or to less than half the space round the eye- 

 being. If this is done, and if by the whole figure is under- 

 stood the given figure together with any addition required for 

 the proof, then my statements will hold, but with one exception. 

 I was wrong in saying that Legendre's proof, given by Mr. 

 Casey, can be treated in the same manner as Sir Wm. Hamilton's. 

 For in this proof a series of triangles is constructed with sides 

 which increase till they become infinite. The reasoning is there- 

 fore not applicable to the sphere. But neither is it to the plane. 

 We have no right to reason about infinite figures as we do about 

 finite ones. O. Hekrict 



Wild Duck laying in Rook's Nest 

 A WEEK ago to-day six wild duck's eggs were taken out of a 

 rook's nest about four miles from here. The rookery is situated 

 on the banks of the River Test. Tlie nest from which these eggs 

 were taken (the bird flew off as the nest was approached) was in 

 a horse-chestnut tree, and was about thirty feet from the ground ; 

 the tree was about twenty-five yards from the river, and was 

 surrounded by others, mostly elm. .\n instance of so unusual a 

 situation for wild duck's eggs miglit, I thought, interest some of 

 your readers. John H. Willmore 



Queenwood College, near Stockbridge, Hants, April 3 

 [Our correspondent has sent us one of the eggs referred to, 

 which we have submitted to a well-known oologist, who is of 

 opinion that the egg is most likely a wild duck's. — Ed.] 



The Remarkable Sunsets 



I LEARN from Mr. Frank Atwater. a teacher in the Native 

 College here, that he observed the "glow" at 5 a.m. on Sep- 

 tember 5, w'hen landing from the steamer at Maalaea, thirteen 

 miles south-east of this. He had arrived in the islands only 

 two days before, and marvelled much if such were the sunrises 

 here. He is the only person I have met who observed it prior 

 to the evening of that day. Mr. Atwater's date is verifiable by 

 the regidar movements of the steam-packet. 



Lahaiua, Hawaiian Islands, March 14 S. E. Bishop 



Cats on the District Railway 



With reference to Mr. Vicar's letter last week (p. 551) about 

 the cats at Victoria Station, I beg to state that there are cats all 

 over the District Railway both in and out of the tunnels, and 

 many of them — familiarly called " Stumpy" by the men on the 

 line — can testify by the shortness of their tails to the hairbreadth 

 escapes they have had from passing trains. Those I have seen 

 are mostly full-grown cats, and only once have I seen a kitten 

 walking on the rails, and that was at night after the traffic had 

 ceased. .At one signal-box which is built on a platform over 

 the line, and the only access to which is by a steep iron ladder, 

 down which no cat could cliinb, there are two full-grown tabbies 

 — toms I believe — and I have often seen them asleep behind the 

 signal bells or even on the handrail of the platform, utterly 

 callous to the trains rushing by underneath. As a rule the men 

 are very kind to them, and give them milk, &c. _ . 



I would add that until quite recently there was a small fountain 

 and circular basin near one of the puniping-engine houses wherein 

 were two fish which had been there for about twelve years. One 

 died last year, and now I see the basin has been converted into 

 a flower-bed by the man in charge. E. DE M. Malan 



Victoria Station, District Railway, j\pril 14 



THE GEODETIC SURVEY OF THE UNITED 

 STATES^ 



WE would congratulate Prof. J. E. Hilgard, the Super- 

 intendent of the Survey, on his first general Re- 

 port on the work of his department, which gives an 

 account of the Survey for the fiscal year ending June 

 1882. We are unable to gather why its issue has been 

 deferred until noiv, but its arrival at the present time is 

 not the less opportune, particularly as the programme of 



' " Report of the SurerintenJent of the Survey," Washington, 1883. 

 556 pp . ,to. 



