654 



SCIENCE. 



[Vol.. II., No. 41. 



fragments of three others wliich appear to be pre- 

 cisely similar. Margaiiette W. Brooks. 



Nov. 1, 18S3. 



Supposed glacial phenomena in Boyd 

 county, Ky. 



A part of the work devolving upon us who have re- 

 cently been tracing the .=:outhern boundary of the glaci- 

 ated area in America, lias been to follow up the reports 

 of glacial phenomena south of our line. 



Boyd county, Ky., having been referred to by a 

 number of authorities as such a locality, I was natu- 

 rally led to visit it a short time since; and I found, 

 to my satisfaction, that that region was never directly 

 glaciated. 



Boyd county is in north-eastern Kentucky, border- 

 ing upon West Virginia, and upon the remarkable 

 bend of the Ohio River where it receives the waters 

 of the Big Sandy. Through the attention of Mr. 

 John Campbell of Ironton, O., and Mr. J. H. Means 

 of Ashland, Ky., I was assisted in making a pretty 

 thorough examination of the region. Upon going 

 back aljout two miles into Kentucky from the Ohio 

 Eiver, opposite Ironton, we find ourselves in a valley 

 two miles wide, running parallel with the Ohio Kiver, 

 and two hundred and twenty feet above it. This 

 valley extends for many miles, reaching the river 

 towards the west at Greenup, and continuing some 

 miles, at least, above Ashland. It is known as Flat 

 Woods. The level is remarkably uniform ; and the 

 hills upon either side of it rise about two hundred feet, 

 with numerous lateral openings towards the Ohio. 

 When upon the farther side, and looking northward, 

 one sees the rooky bluffs of tlie old channel rising so 

 like those facing the river itself, that he can scarcely 

 resist the illusion that he is in the present valley of 

 the stream. The supposed glacial plieuomena consist 

 of numerous water-worn pebbles of quartz and quartz- 

 ite scattered along the whole range of this old valley. 

 Most of the pebbles are small, and perfectly rounded, 

 though some were a foot or more in diameter; and 

 one observed was about two feet and a half through, 

 and only slightly worn.. These pebbles are not found 

 upon the hills back from this channel, on the Kentucky 

 side, nor, according to Mr. Campbell, who is a most 

 competent witness, anywhere in Lawrence county, 

 O., back from the river. Plainly enough, they are 

 the result of water-transportation. Whether they 

 were deposited at the very early period when tire 

 Ohio flowed at the level of two hundred and twenty 

 feet higher than now, and regularly occupied this old 

 cliannel, or whether they were brought into place 

 during the existence of the glacial dam which I have 

 supposed at Cincinnati, I will not venture to say ; 

 though the latter theory would seem more in accord- 

 ance with the facts published by Professor White 

 concerning the old channel followed by the Chesa- 

 peake and Ohio railroad, extending from the Ka- 

 nawha River to the mouth of the Guyandotte in West 

 Virginia. The elevation of the Kanawha-Guyandotte 

 channel is nearly the same as that of the one I am 

 describing, and this seems to be a prolongation of 

 that. At any rate, the pebbles can only be indirectly 

 referred to glacial action. 



Now that attention is directed to this class of 

 investigations, it would seem to be important for 

 Professor Lewis to give tlirough your columns, or 

 somewhere else, publicity to his investigations of the 

 facts supposed to indicate glacial action in Pennsyl- 

 vania fartlier south than the boundary-line indicated 

 by our investigations two years ago. 



G. F. Wright. 

 Oberlin, Nov. 5, 1883. 



Elliptic elements of comet Pons-Brooka. 



While the orbit by Professor Boss, published in 

 Science, No. 34, represents observation so well that 

 there can be no doubt of the identity of the two 

 comets, still it is of interest to know how closely 

 elements derived from observations of the present 

 comet alone agree with those of the Pons comet. 



The arc of anomaly already passed over is only 

 about twelve degrees, — a condition very unfavorable 

 to the precise determination of elements, and inade- 

 quate to determine a reliable periodic time. 



On account of this, in the solution of the equa- 

 tions, A e was considered as a known quantity, and 

 finally an assumed value substituted for it. 



I find the following corrections to Professor Boss's 

 elliptic elements from the normal places given 

 below: — 



Att = —194.0" — 78,768. Ae 



AQ = -I- 19..5" -f- 289,2.33. Ae 



Ai ^ — 57.5" + i55,256. Ae 



AT = — 0.065235 — 108.39 A e 



Ag = H- 0.000716 — 0.04 Ae 



Assuming the eccentricity to be 0.934996, which 

 closely approximates to the true value on the hypothe- 

 sis of identity, we have for Ae, —0.000274. 



Tlie resulting corrections to the preliminary ele- 

 ments are, — 



Att = —172.4" 

 A a = — 59.7 

 At = — 72.6 

 • AT = — 0.035537 

 Aq = + 0.000727 

 Ae = — 0.000274 



and the corrected elements are, — 



After obtaining the preceding I'esults, the equations 

 were solved for the value of A e, with the result 

 A e = —0.000032; but no use w.as made of this. 

 Normal places, ISSS.O. 



These normal places are represented by the cor- 

 rected elements, as follows: — 

 C - 0. 



A a cos S. A S. 



I. —0.5" +1.3" 



II. —1.2 -0.1 



in. -f4.4 -1-0.9 



IV. -0.8 -1.2 



Tlie last two places depend entirely upon Albany 

 filar-micrometer observations. 



In order to form some idea of the accuracy attained 

 in modern observations of faint comets, the follow- 

 ing table of comparisons, with the corrected elements, 

 may be of interest. The comparisons are not very 



