May II, iSSS] 



SCIENTIFIC NEV/S. 



445 



The Crystalline Lens of the Human Eye. — Dr. 

 Tscherning (Comptes Reiidus) has investigated the 

 position of the crystalline lens of the human eye. The 

 crystalline is placed obliquely with reference to the visual 

 line, the centres of the curvature of its surface not being 

 found upon this line. This deviation causes a slight 

 degree of astigmatism which is generally compensated 

 by the astigmatism of the cornea when it, as usually 

 occurs, is more convex in the vertical than in the 

 horizontal meridian. 



Appearance of the Hoopoe in England. — We learn 

 from the Field that this spring — if we may venture so to 

 call it — three specimens of the hoopoe have been seen in 

 England — in Kent, Isle of Wight, and Bucks, respectively. 

 One at least of them has been shot. It would be well, 

 if in addition to the " close time " for birds— which is 

 little more than nominal — certain species, such as the 

 hoopoe, the roller, and the golden oriole were placed on an 

 absolutely prohibited list. 



CROW ROOSTS AND CROW ROOSTING. 



AAHTHIN the past few years much has been written 

 concerning the common crow {Corvus Amcrkaniis) as 

 regards its relation to man ; but until recently little or 

 nothing has appeared pertaining to the roosting-places 

 of one of our most common birds. It is not generally 

 known, even among those who consider themselves 

 somewhat acquainted with the species, that during the 

 winter they congregate in vast numbers at some chosen 

 spot, scattering during the daytime in quest of food, but 

 returning at night to seek rest and protection in each 

 other's company. 



It has been my good fortune to visit two such rookeries, 

 and to observe closely the birds composing it, both at 

 the roost and at a distance, so that a fair idea has been 

 obtained of the place under nearly all circumstances. 



The first of these two that I have mentioned is situated 

 about two miles east of Syracuse, N. Y., in a wood known 

 as "Tamarack Swamp," and lying between the Central 

 and West Shore tracks. This swamp, once extensive, 

 has been cut down to a narrow strip not exceeding four 

 hundred yards in width by one and a half miles long ; 

 hemmed in on the north and south sides by hills, and 

 drained by two constantly flowing streams, it has become 

 what is known as a dry swamp, composed of maples, 

 pines, birches, elms, beeches, tamaracks, and oaks. Mid- 

 way in this strip is a stretch of young pines, averaging 

 twelve feet in height, and th's spot, in preference to the 

 more densely wooded portion, has been chosen as the 

 winter home by the crows. The second (for I wish to 

 draw a comparison between the two before proceeding 

 further) is situated in Arlington Cemetery, at Washington, 

 D. C. Here the ground is entirely different. Not only 

 are the trees of a greaterheight and ofa different variety, 

 but the place itself is located on a hill-side fully a hundred 

 and fifty feet above the water, and facing the Potomac 

 River, from which it is distant scarcely an eighth of a 

 mile. The only points of semblance between the two 

 are that it is on a low elevation in a slight ravine which, 

 being drained by two small streams caused by the eleva- 

 tion, is also perfectly dry. Both rookeries are nearly 

 equal in size, the one at Syracuse covering about fifteen 

 acres, and that at Arlington from ten to twelve. 



A visit to these roosts in the daytime is interesting in 



the extreme, while another paid at dusk, when the birds 

 are coming in, is even more so. 



For convenience in description I shall start with the 

 birds at early morn, following them throughout their 

 wanderings until their return at night. Shortly after 

 daybreak the vast throng of black bestirs itseh"; first a 

 loud clamour betokens that the birds are awake ; then/ 

 with a shake or two 'they launch forth in quest of the 

 morning's breakfast. 



Leaving singly, in pairs, by dozens, and in flocks ot' 

 hundreds, each group wings its way to where the pre- 

 vious day's meals were secured, or starts in search of 

 new feeding-grounds. After they are gone the roost is 

 a sight indeed. On every hand the trees and ground 

 beneath are literally covered with the excreta of the 

 birds, having much the appearance of having been 

 plentifully bespattered with whitewash. The air is foul 

 with the odour, mingled with that of the putrefying- 

 bodies of the dead ones that here and there dot the 

 snow, while among the branches, as well as on the^ 

 ground, are numbers of individuals too weak, emaciated, 

 or otherwise disabled to participate in the daily flight. 

 These are readily approached, and are often to be caught 

 in the hands. 



Nowhere outside a rookery can a fair idea be obtained 

 of the gregarious nature of the crow, for here on every 

 hand is abundant evidence of this trait. Not only does 

 the roost surround us, but the departure of the birds 

 in flocks, and the finding of them together subsequently 

 in the day, is of itself enough to establish this fact. 



A drive through the surrounding country will now 

 give a glimpse of their daily life during winter.. 

 Anywhere and everywhere they may be seen, each in 

 search of that which alone will sustain life ; but, with the 

 usual frozen condition of the ground, this, as a rule, is 

 difficult to obtain. Along the rivers and streams they 

 may be seen walking on the ice in search of a possible 

 dead fish or a stray mussel ; breaking through the ice,- 

 where not too thick, in order to get at the unfrozen mud 

 beneath ; and in many places the surface for a consider- 

 able area resembles the land more than the ice, from the 

 quantities of this material thrown out. Here they of 

 course secure considerable vegetable matter, mingled 

 with an occasional shell-fish ; but the supply is poor at 

 the best, for presently they take wing and fly to a barren 

 field, where for a brief period they turn over the frozen 

 lumps of earth, or endeavour to dig into the icy ground 

 itself. At this season of the year there is scarcely a 

 spot unvisited by them, and the distance travelled in 

 going to and from their feeding-grounds is surprising, I 

 have seen them at a distance of some twenty miles, high 

 in the air, winging their way in the direction of the roost, 

 and have no idea how far they may have come before they 

 were observed. Up to about three o'clock the birds 

 are busy feeding, and the average person would hardly 

 believe that within an hour, or even less, these same 

 birds will be miles away, and in company with tens of 

 thousands of the same species. At this time an inclination 

 to move is manifested by a few who fly away just over 

 the tree tops, calling loudly as if to induce the rest who 

 still tarry to follow. These, too, soon depart, anJ by 

 four o'clock or half-past, the sky is filled with the 

 host en route for the rendezvous. An idea can best be 

 gained now of the countless numbers that nightly resort 

 to this place, for although it is impossible to attain any- 

 thing like accuracy as to the numbers, we know that at 

 \ this one place hundreds (and often thousands) pass over 



