September 7, 1888.] 



SCIENCE. 



119 



connecting point, it is very evident that the animal was constructed 

 last. This overlapping of mounds is by no means uncommon in 

 the North-West. and probably may account for the ' amalgamation 

 mounds ' of some writers. Besides the animal, there are in the 

 same group twenty-three round mounds and ten embankments, as 

 well as four other round mounds which have ' approaches.' or a low 

 embankment, running from each. 



A much less bulky animal (4) is on the S.E. i of Sec. 13, T. 27, 

 R. 9, E.. some ten miles east of Freeport, Stephenson County, and 

 on the north side of Pecatonica River. Its greatest length in an air 

 line is 116+ feet, and the average height of the body lA feet. In 

 the same group with it there is one embankment and seven round 

 mounds, three of which are partially demolished. In one of the 

 latter a fine hematite ' plumb-bob ' was unearthed, in connection 

 with a human skeleton which was badly decayed. Hematite relics 

 in this region, and especially plumb-bobs, are exceedingly rare. 



Near these mounds, but at the foot of the slope, there is a fine 

 boiling spring of pure cold water. 



^'ery few of these Illinois effigy mounds are in a good state of 

 preservation ; but 1 looked around long enough to find ten of them 

 worth surveying, of which the four now given are the best suited 

 for publication as types. 



Ill surveying mounds of this class it has been a special object to 

 get their true outlines as near as possible, without any preconceived 

 ideas or fanciful imaginings as to what animal or other object 

 they were intended to represent. To do this it is necessary to de- 

 termine where the artificial ground ends on the natural surface. It 

 is hardly possible, however, for the reader, even with the aid of 

 faithful diagrams, to form an adequate idea of the beauty and sym- 

 metr)- of the efligies as they appear to the eye when in their undis- 

 turbed state. T. H. Lewis. 



St. Paul, Minn., July 31. 



The Coal-Measures of Kansas. 



The drilling of a 2,ooo-foot well at Emporia, Kan., has furnished 

 an excellent section of the coal-measures of this State. The loca- 

 tion of the section, unfortunately, can be given but approximately. 

 Beginning somewhere in the upper half of the upper coal-measures, 

 it ends in the lower third of the lower coal-nieasures. The section 

 is very interesting, however, independently of its position in the 

 formations. 



In the depth of nearly 2.000 feet there are it2 strata with an 

 .iverage thickness of nearly 18 feet. Of these strata, 50 are shale. 



50 limestone, and 12 sandstone. The limestone strata average gi 

 feet in thickness ; the shale, 25 feet ; and the sandstone, 24 feet. 

 In the upper thousand feet are i of the shale strata, /^ of the lime- 

 stone, and -{'^ of the sandstone strata; but in the first thousand feet 

 are-f'j of the shale, nearly i of the limestone, and 1 of the sandstone. 

 The total thickness of the shale is 1,242 feet, limestone 465 feet, 

 and sandstone 286 feet. Mingled with the shale are three beds 

 of coal in the first 500 feet, and one bed in the last 500. The 

 thicknesses average less than one foot. 



The section teaches that the conditions under which the coal- 

 measures were deposited were exceedingly variable, and that the 

 tracing of the strata through eastern Kansas will not be a holiday 

 task. 



These deposits, even including the limestone, are mostly shallow- 

 water accumulations, and are quite rich in fossils, especially the 

 limestone. Incrusting corals, crinoid joints, and brachiopod and 

 conchifer shells are especially abundant. Trilobites are rare. 



L. C. WOOSTER. 



Eureka, Kan., Aug. 31. 



Radiant Energy. 



In your issue, Aug. 17, Prof. S. P. Langley, in his presidential 

 address at the late meeting of the American Association for the 

 Advancement of Science, puts his case a little too strongly in favor 

 of Draper. I think, when referring to Melloni's statement of the 

 relation between light and heat forms of radiant energy, made in 

 1S43. He says, — 



'• So far as I know, no physicist of eminence re-asserted Mel- 

 loni's principle till J. W. Draper, in 1872. Only sixteen years ago, 

 or in 1873. it was almost universally believed that there were three 

 different entities in the spectrum, represented by actinic, luminous, 

 and thermal rays." 



As a student at Dalhousie University, Halifax, Nova Scotia, be- 

 fore Draper's publication of 1872, I found Melloni's principle not only 

 " re-asserted." but accepted. I fail to understand how it could be 

 otherwise in the United States, when Tyndall's lectures and demon- 

 strations in the Royal Institution were published in 1863, a quarter 

 of a century ago; when the Smithsonian Report of 186S, twenty 

 years ago, published Tyndall's Rede Lecture before the University 

 of Cambridge in 1865, with translations of articles by Cazin and 

 Magrini bearing on the same subject. But, more than that, Tyn- 

 dall's lectures were published in a neat volume of some five or six 

 hundred pages, by D. Appleton & Co. of New York, in 1870, two 

 years before Draper's publication. I thought Professor Langley 

 might have eminent " American physicists " in his mind : but his 

 reference to the English cyclopajdia of 1867 immediately before, 

 suggests no such limit to his statement. A. H. MacKay. 



Pictou Academy, Nova Scotia, Aug. 22. 



[Mr. MacKay 's letter may elicit more information on an interest- 

 ing point, but attention should be drawn to the fact that he offers 

 no evidence (i.e., cites no passages) to show that the lectures he 

 mentions do quote any " physicist of eminence " in plain support 

 of the doctrine in question. A statement as explicit as Melloni's or 

 Draper's is what is wanted. Statements which might mean this 

 (or any thing else) are plenty. — Ed.] 



The Laws of Corrasion. 

 Upon opening my copy of Scieitce this morning, I am greeted 

 with your note on Major Powell's " first formal announcement of a 

 new law in the hydraulics of rivers " upon the relation between their 

 corrading power and sedimentary load. I think you will find this 

 principle fully stated by Major Powell in his ' Report on the 

 Geology of the Uinta Mountains ' (Government Printing-Oflfice, 

 1876) ; but my object in writing is to draw your alteniion to the 

 recognition of this "new law " in Chapter X\'I., an<l especially p. 

 226. of the new • Physical Geography ' of \'an .Antwerp. Bragg. & Co. 

 The law as enunciated in the first paragraph of Scit-itce (No. 290) is 

 only true within certain limits, for ihe sedimentary lo.id of a stream 

 may become so great that it requires all the energy of the current 

 to simply transport it, and hence there is little or no corrasion. 

 The rivers of the Great Plains, —as Platte. Republican, Arkansas, 



