140 



SCIENCJE. 



[Vol. I., No. 5. 



quence, unable to obtain its position except by esti- 

 mation. 



At twenty minutes past seven I estimated it to 

 have been in about R. A. 22 b. 57 m., Dec. + 29° 

 50', as determined by comparison with Argelander's 

 charts, no allowance for precession being made. It 

 was 2° 37' almost exactly north of Beta Pegasi, as 

 roughly determined by the size of the field of my 

 comet ej'e-piece. Its motion is slowly eastward, 

 probably north-east; but its altitude was so low, 

 and the hour being so near moonrise, I could not 

 determine its exact direction. 



It presented a beautiful appearance through my 

 4j4-inch achromatic. Lewis Swift. 



Warner observatory, Rochester, Feb. 24. 



Movement of the arms in ivalking. 



In Science, Feb. 9, Mr. F. W. True recognizes the 

 'movement of the arms in walking' as a functional 

 relic of quadrupedal locomotion; urging thereby a 

 modification of the expression of Professor Dana, 

 sanctioned by Dr. Gill, that "man stands alone among 

 mammals in having the fore-limbs not only prehen- 

 sile, but out of the inferior series, the posterior pair 

 being the sole locomotive organs." And the questions 

 are asked, "Have we not at least a ghost of a pre- 

 existing function? Does man walk by means of his 

 feet and legs alone?" Viewing the question from 

 the developmental standpoint, it seems to me that the 

 strongest evidence appears in the first locomotor-acts 

 of the child. Before bipedal progression is learned, 

 the child r/oes on all-fours, and is an actual mammal- 

 ian quadruped. At the beginning of this the prehen- 

 sile power of the fingers is very imperfect. Men have 

 been known to educate their toes to do more than the 

 fingers can at that stage of functional development. 

 At that time the palms are of more value as soles 

 than for holding things. In the beginning, also, the 

 arms in some children are better legs than are the 

 hind-limbs, being more easily used. For example, it 

 is more common for children to creep on the knees 

 Jhan on the elbows ; but some learn remarkably early 

 to elevale both knees and elbows, to creep on the 

 soles and palms. My own boy walked on his soles 

 and palms from the start, and never upon his knees. 

 The speed with which he finally learned to run in 

 this way was remarkable. After learning to move 

 somewhat on his hind-legs, when he got in such 

 haste as to make bipedal balancement difficult or 

 uncertain, he would take to all-fours, thereby making 

 better speed with less danger of a fall. 



U.S. dept. of agric, Washington, \Sf. S. BaknAED. 



The heart as a locomotive organ. 



Every one has observed that the tendency of the 

 heart to beat while walking ' is a most natural one.' 

 'The action is rhythmical,' the number and force of 

 the pulsations varying with the velocity of the walk. 

 'It is also involuntary;' but, although proper locomo- 

 tive movements are usually in a high degree voluntary, 

 this consideration need cause us no uneasiness, if we 

 reflect, that, when its action is from any cause sus- 

 pended, ' an air of stiffness' is soon imparted to the 

 whole body. 



In view of these facts, does it not seem that the 

 statement (Science, p. 11) that " man stands alone 

 among mannnals in having the fore-limbs not only 

 prehensile, but out of the inferior series, the posterior 

 pair being the Hole locomotive organs," should be 

 further modified, and the heart assigned its proper 

 place between the swinging arms as a true loco- 

 motive organ ? O. Hargeb. 



New Haven, Feb. 2S. 



The copper-bearing rocks of Lake Superior 



There are one or two statements in Mr. Selwyn's 

 remai-ks on the age of the rocks on the northern shore 

 of Lake Superior, in the number of your journal for 

 Feb. 9, which I cannot suffer to pass nnchallenged. 



I cannot enter here into a general discussion of the 

 much-vexed question of the age of the Lake Superior 

 copper rocks, — I have discussed it at length else- 

 where,' — but I must take issue with the statement 

 that there is "no evidence whatever of their holding 

 any other place in the geological series" than that 

 which "includes the Potsdam and Primordial Silu- 

 rian." My own conclusions in this connection, after 

 an examination of most of the circuit of Lake Su- 

 perior, are : — 



1°. That the copper-bearing rocks underlie uncon- 

 formably — and with an immense unconformity — a, 

 series of sandstones holding Cambrian fossils. These 

 fossils may not correspond to the oldest Cambrian 

 fossils known elsewhere, as argued by N. H. Winchell 

 in the report quoted, but they are distinctly Cambrian; 

 and if the copper-bearing strata are to be called Cam- 

 brian, then we must stretch that term over a most im- 

 mense unconformity, in order to include a rock-series 

 holding no fossil evidence of its Cambrian age, — a. 

 thing which appears to me very unreasonable to do. 

 This unconformity is best seen in the St. Croix river 

 region of western Wisconsin, and thence north-east- 

 ward. Although attention was drawn some years 

 since by Sweet, Chamberlin, and myself,- to the 

 strikingly conclusive occurrences of this region, our 

 evidence has been ignored by others who have never 

 examined the region, and who continue to approach 

 the question from the eastward, or, in other words, 

 from the same direction as a succession of geologists, 

 from Houghton to Selwyn, all of whom have felt 

 baffled. It is interesting to note in this connection 

 that N. H. Winchell, the only geologist who has gone- 

 to the St. Croix since our report was issued, confesses 

 to the unconformity,^ although he had strenuously 

 refused to believe in it before visiting the I'egion. It 

 does not seem to me that any geologist can honestly 

 deny this unconformity until he has done as we have 

 done; viz., followed the copper-bearing strata, with 

 all their characters preserved, mile by mile, from the 

 typical region of Keweenaw Point, to their junction 

 with the fossiliferous Cambrian sandstone of the St. 

 Croix valley. 



2°. That the copper-bearing strata also underlie un- 

 confonnably the 'eastern sandstone' of the south shore 

 of the eastern half of Lake Superior. Winchell has 

 argued a difference of age between this sandstone and 

 that of the St. Croix valley. However this may be,— 

 and I have myself seen no evidence that the one of 

 these sandstones is not merely the direct downward 

 continuation of the other, — the work done by my- 

 self and assistants along the contact line of the copper- 

 bearing rocks, and the eastern sandstone from Bete 

 Grise Bay westward to the vicinity of Lake Agogebic, 

 has served to convince me that there is here atso an 

 unconformity as great as the other. 



3°. That the time-gap between the copper-bearing^ 

 series and the Hui'onian was too long to allow of our 

 classing them together, — for it certainly covered a 

 considerable amount of denudation and altei-ation, — 

 but it is still doubtful if this gap was long enough to 

 cover the folding of the folded Huronian. The great- 

 est confusion prevails as to the use of the term Hu- 



1 The copper-bcarinc; rocks of Lalce Superior, — vol. v.. mono- 

 graphic publications of tlie U. S. geol. survey ; also Third annual 

 report of the same survey. Both of these publications are still 



" Geology of Wisconsin, vol. i 



' Loo. cit., p. 134. 



