542 



SCIENCE 



[Vol. XVI II. No. 463 



SCIENCE: 



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MA.STODON EEMA.1NS ON NEW YOEK ISLAND. 



On Nov. 27 last Lieut.-Col. Gillespie of the Engineers' De 

 parlment, U.S.A., addressed a letter to the American Mu- 

 seum of Natural History, offering the remains of a mastodon 

 tusk which had been found during the excavation for the 

 Harlem Ship Canal at the upper end of New York Island. 

 Col, Gillespie infornts me that the specimen was found at a 

 depth of sixteen feet below mean low-water, at the eastern 

 end of Dyckman's Creek, at its junction with the Harlem 

 Eiver. 



The portion of the tusk preserved and received at the 

 museum is nearly three feet long, and has a diameter of 

 seven and a half inches full, at its largest part; being the 

 upper or socket end of the tusk, and is well preserved, 

 although much shattered by drying and rough handling by 

 the workmen before it came to the attention of the engineers 

 in charge of the work. 



A few days after the tusk was received at the museum I 

 visited the excavation, and, by the courtesy of the engiueei's 

 in charge, Messrs. A. Doerflinger and J. McC. Taylor, 

 learned the particulars of its occurrence. 



The excavation at this point is tlirough the salt meadow 

 of the Harlem River, showing from four to six feet of 

 meadow sod and silt filled with the roots of the meadow 

 grass; below this there is a deep bed of incipient peat, of 

 which, at the spot where the tusk was found, there was fully 

 twelve feet; next below comes a bed of sandy clay of very 

 variable thickness, but at the spot in question measuring 

 only eighteen or twenty inches in thickness. This clay rests 

 immediately on the submerged slope of the dolomitic lime- 

 stone ridge which forms the upper end of Maniiattan Island, 

 and extends northward beyond the Spuyten Duyvil Creek. 



The tusk was found imbedded in the peat with the socket 

 or "butt "end down, and slightly entering the sand, the 

 shaft being in the peat and at an angle of about seventy de- 

 grees to the horizontal, showing that it had settled through 

 the peat until it came in contact with the sand. 



From the indicitioiis furaishsd by the conditions of its 

 occurrence [ s'lould conclude that the tusk had not been trans- 



ported from any other locality after the death of the animal, 

 as there is no abrasion shown on its surface. Moreover, the 

 peat in which it was imbedded is in the condition of its 

 original formation, is clean and unmixed with any foreign 

 matter, being entirely of vegetable origin ; and containsquan- 

 tities of seeds, apparently of Carices, or sedges, and grasses, as 

 well as a few nutlets of some bush or shrub not yet determined, 

 and examples of the elytra of beetles. At the top of the peat 

 occur numbers of the stumps and roots of forest trees and 

 fragments of wood. No evidence whatever is found of any 

 marine substance below the roots of marsh grass, not a ves- 

 tige of any kind of mollusks, marine or fresh water, can be 

 detected, although now living and abundant in the salt wa- 

 ter at the surface. The sandy clay betvveen the peat and the 

 surface of the limestone appears to me to be the result, 

 principally, of the decomposition of the limestone in place, 

 and not transported sand. Glacial markings are discovera- 

 ble on the surface of the limestone a short distance south of 

 the locality, where the soil has protected it from the action 

 of the weather, but where the ledge has been uncovered by 

 the re.moval of the peat and sand, it shows a deeply rotted 

 surface covered by the sand, 



Dyckman's Creek was an artiflcially excavated channel, 

 made about 1818, for the purposes of a tide mill, through a 

 natural depression at that point, and not a natural stream; 

 consequently, it could have had no agency in the transpor- 

 tation of the tusk; and it seems probable that the animal to 

 which the tusk oEce belonged either died near the spot, or by 

 some accidental injury had it broken from its socket near 

 where it was found. 



The exact location of its occurrence is in the canal, about 

 fifteen feet from its northern side, and about ten feet west of 

 the centre of Broadway. 



In April, 1885, Elisha A. Howland. then principal of 

 grammar school No. 68, at 128th Street, between 6th and 7th 

 Avenues, brought and donated to the museum the lower ex- 

 tremity of a mastodon tusk, nearly fifteen inches long by 

 four in its greatest diameter, which had been found shortly 

 before at Inwood, N.Y., while cutting a ditch through a 

 peat bed near tlie Presbyterian Church at that place. This 

 fragment shows fresh breaking at the upper end, and was 

 undoubtedly much longer when first found. 



R. P. W. 



CO-OPERATIVE OBSERVATION OF THE SO-CALLED 

 LUMINOUS CLOUDS.' 



Since 1885 curious cloud formations have been seen on 

 summer nights in both the northern and southern hemi- 

 spheres, in evident connection with those phenomena which 

 followed the great volcanic eruption at Krakatoa. The in- 

 tense brightness of these formations, considering the position 

 of the sun, denoted that they were situated very far above 

 the earth's surface. Probably these clouds consisted of 

 erupted particles thrown to a very great height and there 

 illuminated on summer nights by the sun. 



These cloud-like formations, commonly called luminous 

 clouds ate extremely interesting, both on account of the ex- 

 traordinary height at which they have for years been moving 

 above the surface of the earth (more than eighty kilometres) 

 and of the movements themselves. A very important point 

 about these clouds is that they are — so far as we yet know — 

 visible in each hemisphere only in the summer. It is the 

 more important that these phenomena should be carefully 



' Prom Nature, Dec. 3. 



