| Aug. 21, 1873] 
NATURE 
331 
acceptation of the term; in other words, that it 
does not result from the shock produced by the opening 
of the aortic valve, but that it is coincident with the flow 
of liquids, one reason being, as the author remarks, that 
_ the most violent impulse in an artificial model or schema 
_ ofthe circulation so communicated, as not to cause any flow 
_ of liquid, produces no upstroke, but only a slight quivering 
ofthelever. However, that the primary oscillation of the 
lever in a sphygmograph trace is not, in a great measure, 
‘a genuine representation of the movements in the artery, 
it is equally impossible to believe, for in very slow 
pulses, where the main rise is not very decided, this wave 
is particularly pronounced, being gradual in its rise, and 
_ more gradual and paraboloid in its fall. Itis also seen 
_ equally clearly by employing a reflecting sphygmoscope, 
‘in which the ray of light which acts as the long arm of 
the lever, has no weight, and consequently cannot produce 
any oscillation, Another great objection is that the notch 
_ between the first and second (the percussion and the 
tidal) waves always occurs at the instant at which the 
aortic valve closes at the heart,* the time it appears after 
he commencing pulsation varying with the length of the 
] pulse-beat. In fact, the tendency of all observations is to 
“make it evident that the second or tidal wave is a post- 
"systolic act, being the oscillatory indication of the 
secondary tidal wave, which appears as such in the 
dicrotic rise, and originates from the closure of the aortic 
valve, as Dr. Galabin agrees with most in thinking ; 
though Dr. Sanderson holds the very different view that 
the second beat is a restoration of equilibrium which takes 
_ place by increase of pressure towards the heart and dimi- 
-nution towards the periphery, a consequence of the sudden 
projection towards the capillaries of the blood during the 
systole. 
: Or: Galabin remarks that, “if the sphygmograph used 
have a secondary spring to keep down the long lever, the 
tidal wave may be replaced by two or even by a jagged 
line. Such a spring is better omitted, because it is apt to 
introduce oscillations of its own.” It is this idea which 
has misled him. Tracings taken as he proposes appear 
much in favour of his explanation, but they are so be- 
cause they are in reality less truthful than they might be. 
We have never seen the least indication of any imperfec- 
tions caused by the employment of the small spring, but 
we have seen the “ percussion” wave divided into two by 
it in very slow pulses, the former being a small true 
shock-rise, and the latter the real primary rise. 
In conclusion, we cannot refrain from quoting a remark of 
Dr. Galabin, which, from the precise way in which it sets 
the question referred to at rest, is worthy of being quoted 
in every text-book. Referring to the rhythmical contrac- 
tion observed by Wharton Jones and Schiff in the wing 
of the bat and the ear of the rabbit, and its supposed in- 
fluence in assisting the circulation of the blood, he re- 
marks, “ Now a peristaltic wave in a tube would tend to 
produce a current in the liquid of its own velocity, and it 
would, therefore, accelerate a slower current, but retard a 
quicker one. Therefore, no peristaltic wave could accele- 
rate the arterial stream, unless it travelled with the ve- 
locity of the pulse-wave. It is thus evident that no such 
slow rhythmical motions as have been observed could as- 
sist the arterial ow. And it is inconsistent with the usual 
character of involuntary muscle to suppose it capable of 
transmitting a very rapid wave of contraction, The 
arteries themselves indeed, when made to contract by 
artificial stimulus, do so slowly and gradually,” 
A. H. G. 
AMERICAN EXPLORING EXPEDITIONS IN 
THE GREAT WEST ; 
1 epee are several imporiant expeditions more or less 
employed upon scientific work in ,the least known 
portions of the Western territories. From some of these 
* See Proc. Roy. Soc., 1871, p. 320. 
parties, a considerable amount of fragmentary infor- 
mation comes at irregular intervals ; but in other cases 
the explorers prefer to withhold details as to their move- 
ments and work, whether scientific or otherwise, till 
after their return, when their report can be prepared 
officially. There is, however, a general and widespread 
interest taken in these explorations. It seems desirable 
for the sake of a clear understanding of news from time 
to time received, that a general éswmé of the status and 
work of at least the more prominent expeditions should be 
presented. : 
What is known as the Yellowstone Expedition will first 
be mentioned, because in size it is much the most for- 
midable. It proceeds through a region where itis deemed 
advisable to strike terror among hostile savages, and 
with that view has a military force of 1,900 men. Its 
movements also have reference to the establishment of 
two new military posts in the north-west, for which 
purpose Congress has appropriated 200,000 dollars. The 
force serves as an escort to surveying parties of the 
Northern Pacific Railroad, with reference to its comple- 
tion from the town of Bismarck on the Missouri River 
in Dakota—about the centre of that territory, and near 
the lorst parallel west of Washington—to the Rocky 
Mountains ; a distance of between 500 and 600 miles, on 
a line drawn in general east and west, and south of 47° 
N. lat. 
This line may be divided into three parts ; (1) from the 
Missouri River to the Yellowstone, about 200 miles, 
coming into the territory of Montana; (2) along the 
Yellowstone River about 100 miles ; (3) thence west-ward, 
reaching the Rocky Mountains south of the town of 
Helena. At the date of latest advices, the expedition had 
passed over the first division, and was on the banks of 
the Yellowstone. The navigability of that river had just 
been demonstrated by the successful ascent of a steam- 
boat, built at Pittsburg for the purpose, which brought 
supplies from Fort Buford. 
Of the scientific party accompanying the Yellowstone 
Expedition, the following names may be mentioned :— 
Dr. J. A Allen, of Cambridge, Mass., in charge of 
zoology, botany, and paleontology, ani chief of the 
scientific party; Dr. L. R. Nettre, mineralogist and geo- 
logist ; W. R. Pywell, of Washington, photographer; E. 
Konipucky, of the Museum at Cambridge, artist; and 
C. W. Bennett, taxidermist. 
The Hayden Expedition, as that under the manage- 
ment of Dr, F. V. Hayden is generally termed, might be 
more properly designated as the United States Geolozical 
and Geographical Survey. It has a much larger scien- 
tific staff than any of the other expeditions. Its history 
dates from 1867, when what was then the territory of 
Nebraska was the subject of a survey by the United 
States, Prof. Hayden being appointed chief geologist to 
the survey under the Act of Congress by which the under- 
taking was authorised. The next year the survey was 
extended into Wyoming Territory, and in 1869, into 
Colorado and New Mexico. In 1870, a more careful 
survey of Wyoming Territory was made; and in 1871, 
portions of Montana, including the natural wonders of 
the Yellowstone region, became the subjects of explora- 
tion ; ultimately resulting in the setting apart as a public 
pleasure-ground of the Yel'owstone National Park, a 
district of 3,575 square miles. The survey of 1872 
reached the region of the Yellowstone by separate routes 
of two divisions, of which one proceeded from Fort 
Ogden, Utah, and passed up the Valley of the Snake 
River in Idaho Territory; the other started from 
Boseman, a town in Montana near the Rocky Mountains, 
and on one of the Upper Forks of the Missouri River. 
The appropriations for this series of surveys have been 
increased year by year, starting with 5,000 dollars in 1867, 
and rising to 75,000 dollars for the survey now takin 
place. , 
