March 2, 1894. - 
temperature was encountered. ‘The heat and sulphurous 
vapors are almost stifling. Here it is that mineral depo- 
sition is still going on. Most noticeable is it in the case 
of sulphur, minute sparkling crystals of which line the 
cavities. Not only are cinnibar and sulphur present but 
gold also in small amount. In the lower tunnel a brown 
bitumen is abundant in the rock cavities. It results from 
the vaporization of bituminous matter in the deeper 
seated portions of these cretaceous rocks. The cinnibar 
for which the mine is being developed occurs impregnating 
the silicious sinter and aragonite, evidently having been 
formed with them. In exploring the deeper and hotter 
portions of this mine but little stretch of the imagination 
is needed to picture oneself within the very bowels of the 
earth. 
In the upper tunnel is well illustrated the cooler condi- 
tions requisite for the deposition of sulphur. While in 
the lower tunnel it is found in comparatively small 
amount, in the upper the rock is richly impregnated with 
sulphur crystals. The cavities of the brecciated sinter 
fairly sparkle with them. 
On the north extension of the Elgin, sulphur works have 
been opened for the mining of sulphur, which exists mixed 
with soft friable.tufas of a variable appearance and com- 
position. 
A careful study of the Elgin mine would be a means of 
making one familiar with the formation of sulphur and 
cinnibar in the coast ranges. While the conditions are 
of course not all alike, the springs varying in temperature 
and composition, the manner of deposition is every- 
where much the same for these minerals. 
LETTERS TO THE EDITOR. 
+*, Correspondents are requested to be as brief as possible. The writer's name is 
in all cases required as a proof of good faith. 
On request in advance, one hundred copies of the number containing his communi- 
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The Editor will be glad to publish any queries consonant with the character of the 
journal. 
The Data of Bird Flight. 
In Sczence for Jan. 26, 1894, p. 46, Mr. C. F. Amery, 
commenting on Professor Langley’s recent ‘‘ Internal 
Work of the Wind,” makes inroads into what had seemed 
to be the fund of accepted observational data in regard to 
bird flight—soaring flight in particular. Possibly there is 
not to be found in print any deliberate and detailed sum- 
mary of the bare, unexplained, facts of the bird’s per- 
formance, upon which there is agreement among recent 
students of the subject, but a considerable list of accordant 
observations may readily be made up from the several nota- 
ble papers of the last few years, which have dealt with the 
general problem from a new experimental point of view. 
The interested public is aware that the whole matter of 
air-navigation has of late been taken up de zovo, by search- 
ing inductive methods, and it is fairly to be inferred that 
renewed observation of soaring birds, in connection there- 
with, has been more orderly and appreciative of essentials, 
hence more definite and trustworthy. It is, therefore, 
disconcerting to the non-specialist to find seemingly 
fundamental data of the investigation discredited. 
Mr. Amery affirms, in effect, that the soaring bird can- 
not keepup to a level course in straight onward flight, 
whatever the motion, bodily or differential, of the air 
through which it passes; that it is by circling that altitude 
is maintained or gained. Yet it is a matter of frequent 
comment in regard to the sailing flight of certain sea birds, 
notably the ‘‘ wandering” albatross, that they perform 
just this feat. Circling is the persistent habit of the soar- 
ing land birds, of which, among many competitors, the 
eastern vulture is perhaps past-master for varied skill; 
and there is conspicuous suggestion of a cause-and-effect 
SCENE: 
121 
relation in sustained circle-soaring. But the sea bird 
travels a wider field, and more commonly sails a straight 
course; moreover, its normal plane of flight is not at high 
altitudes, but within the possible vertical range of the sea- 
going observer, whose interest, furthermore, the bird re- 
ciprocates—in fact, if not in kind—so that its perfermance 
is brought into notice at short range. And the burden 
of testimony is that, in air conditions ranging between 
extremes of storm and calm, the albatross and other sea 
birds do, in fact, for long distances, travel the wind on 
undeviating courses, in virtually effortless flight. It has 
been my opinion that this paradoxical statement was yet 
a statement of fact, and that it was only the diverse ex- 
planations of this and other similarly puzzling phenomena 
that were in controversy. 
For several years [have been an attentive observer of 
soaring birds, but my incentive has been limited to the 
interest of verification for myself of what were believed 
to be the accepted data of the modern investigation. Mr. 
Amery’s dictum puts us (or at least myself) all the more 
into disorder because there is seemingly no recognition 
that, from such a postulate, we must undermine a body of 
doctrine. 
If, perhaps, it is I, as a non-specialist in the audience, 
who am the one in fault, then there is compensation in 
the added valtte my verification-notes will have acquired, 
as contributions to a question still open. On that con- 
tingency I draw upon them here. 
The best representatives of the air-sailers, among sea 
and land birds respectively, of which I have had oppor- 
tunity for close observation, have been the remarkably 
tame gulls of San Francisco Bay, and the hawks of the 
Rocky Mountain region. The gulls are tamed by the 
ferry passengers, who feed them with crumbs, to be caught 
onthe wing. They follow alongside, a little beyond arm’s 
length. Ina wind of moderate strength (I am not able to 
speak with certainty about directions) they will for some 
minutes maintain, without wing stroke, fixed positions, 
with reference to the boat, as steadily as though perched 
on the rail. In review of the lines of spectators, they 
abruptly drift forward and backward, and rise and sink 
between deck levels. As with flies in the air of a railroad 
car, the general forward course appears to be no matter of 
their concern. ‘These subordinate motions are all in the 
vertical plane of the general forward motion—parallel to 
the boat’s side, just beyond cane and umbrella reach. To 
the vertical plane, the line of the wings is held unvaryingly 
at right angles. Upon this steady horizontal axis there 
is, however, rotation at the shoulder; but barely percepti- 
ble in amount, and quick, with momentary pauses, dis- 
continuous, and unrythmical—apparently an exceedingly 
alert and vigilant balancing process. ‘The tail is slightly 
and slowly opened and closed, fanlike; and slightly, but 
quickly, tilted sideways, and up anddown. The head is 
moved deliberately, in all directions, with the effect of a 
quiet glance, independent of the general nervous activity. 
At an increased distance, as with the leaning ship that has 
carried the roar of the wind in its sails beyond hearing, 
only the easy poise is noted. Occasionally a gull will 
venture to alight on the pilot house. He wheels into 
position, and, the feet hanging downward, connection is 
made through the last inch or two carefully, as in train- 
coupling with both sections in motion; but the wings 
remain fully extended until the body is at rest, when they 
are folded in gently, as though pains must be taken to 
avoid again catching the wind. If startled from his perch, 
he makes a strong wing stroke, and slants swiftly back- 
ward and downward; but the usual mode is a repetition, 
in reverse, of the alighting process: without the initial 
impulse of a stoop and spring, he floats outward and up- 
ward, ahead of the boat; then, perhaps, circles into place 
