.....Canoe valley.

Orthoceras multicameratum, *.

Pleurotomoria umbilicata,*.

Rogers, (p. 817) mentions the following, not as yet observed:

LOWER LIMESTONES. CALCIFEROUS. (Auroral, II.)

In the above list no mention is made of the organic animal remains of the Coal Measures, no collections in these having been as yet systematically made. Those observed by Prof. J. J. Stevenson in Washington and Greene Counties will be recorded in his forthcoming report of 1875.

An important collection recently sent in by Mr. Carll has not yet been sufficiently studied to be included in the present notice.

Those marked * are mentioned by Rogers.

Contributions to the Physical Geography of the United States, by Charles Allen, Assistant in charge of the Collection and Collation of Railroad and other Levels for the Second Geological Survey of Pennsylvania.

BY J. P. LESLEY.

(Read before the American Philosophical Society, January 15, 1876.) In presenting to the attention of the members Mr. Allen's list of Pennsylvania levels, I have only to say that the progress of physical geography in the United States has been so rapid, of late years, as to attract the attention of the Scientific world at home and abroad, and that its connection with the progress of geological science is so intimate, that working geologists hail with lively pleasure the publication of all hypsometrical records of a genuine kind, whether old or new. For want of government bureaus of statistics the greater part of such records have been irrecoverably lost. Of the tentative work of our railway, canal, slackwater and turnpike companies, done between 1830 and 1860, scarcely a trace remains; although, if its records could be recovered and printed, they would furnish copy for hundreds of volumes. Since 1860 the destruction has not been so complete, but has been nevertheless very great. There are recent important surveys of which no records can be found, even in the offices of the companies for whom they were made.

This important subject has received well-deserved attention at the hands of the chiefs of the United States Exploring Expeditions, who are mapping the interior of the Continent. But some efficient organization is required for the preservation and publication of levels in the States lying between the Atlantic and the Mississippi.

The State Geologists of Ohio and North Carolina, also, have published valuable hypsometric tables.

A beginning has now been made in Pennsylvania; and the following pages contain the records of the height above some assumed datum, reduced to tide level, of all stations on railways in the State, and in its immediate vicinity.

These records have mostly been obtained by personal examination of the profiles preserved at the offices; and in some cases, by letter, from superintendents and engineers. The greatest interest in the Collection has been manifested by members of the profession of Civil Engineering to whom application has been made; and in some instances, where records were wanting, new levelings have been ordered and the results transmitted.

Short headings are prefixed to the records, stating place, date and authority; and foot notes appended to them, stating difficulties of adjustment, incongruities, or doubts.

That a work of this nature should have the advantage of first publication in the transactions of the oldest Scientific Society of America, whose first President was Benjamin Franklin, and whose hall stands side by side with the ancient Capitol of the United States, is my reason for asking that this first systematic attempt on a large scale to render permanent and useful to all engineers and surveyors the scattered and perishable records of heights above sealevel of several thousand points in our valleys and on our mountains should be accepted by the Society.

It must be understood, however, that these lists require thorough re-examination and correction before they can be adopted as constants of science for the future. There are considerable difficulties yet to be encountered by such as undertake to harmonise the data of our railway surveys. Indeed, considering the imperfect way in which such surveys are necessarily made,-the accumulation of errors of instrumentation and personal equation along every long spiritlevel line, the uncertainty even of the tide-level datum at every head of tide, the frequent lack of notes stating whether railway levels cross each other on grade, or not,— and the not uncommon fact that, after location-surveys have

been made, the road-beds have been tempered up, or down, to suit convenience, and no record of the fact been kept, except in the memory of some division engineer no longer in the employ of the Company,—it is surprising that the errors of terminal or crossing adjustment are so few and small. But to render the record perfect all such errors, however few and small, must be eliminated; and this can only be accomplished by a zealous interest taken in the subject by resident engineers; who are therefore earnestly requested to co-operate to this end.

Geologists are dependent for the goodness of their fieldwork on accurate base-line levels. And it is to be hoped that a complete exhibition of the surface contour of Pennsylvania will sooner or later be obtained from a collation of the thousands of transit-lines and barometer-lines now in progress in all the districts occupied by the Assistant Geologists of the Survey. All their lines of levels are, however, based on the railroad records, and the publication of these in a corrected form is a necessary preliminary step.

If movements are still taking place in the crust of the earth, and the frequent occurrence of slight earthquake shocks, in all the States of the Union, seems to speak in favor of the supposition,-physical philosophers are peculiarly interested in an early establishment of a universal hypsometrical record. From this point of view, also, it would seem especially germain to the origin and history of the American Philosophical Society to initiate such a record.

The net-work of Surveys which cover Pennsylvania may be divided into nine systems:

1. The Pennsylvania Central east and west system, from Trenton through Philadelphia, Harrisburg, Altoona, Pittsburgh, to Steubenville, and Youngstown, in Ohio; with numerous longer or shorter side branches.

2. The Reading Railroad northwest and southeast system, with many short branches in the Schuylkill Anthracite Field, and through the country in front of it between the Delaware and Susquehanna Rivers. It has been extended also to the

waters of the Upper Susquehanna, and will penetrate into New York State.

3. The North Pennsylvania north and south system, with numerous branches in the Lehigh and Wilkesbarre Anthracite Fields, in connection with the two Lehigh Valley Railroads, extending into the State of New York.

4. The Northern Central north and south system, extending from Baltimore, in Maryland, to Elmira, in New York, with several short branches.

5. The Philadelphia and Erie northwest system, with important branches crossing to the Alleghany River, and into the State of New York.

6. The Alleghany River north and south system, from Pittsburgh to the Oil Region, and Buffalo in New York.

7. The Baltimore and Ohio system, with its Connellsville branch to Pittsburgh, and its short coal and coke branch. 8. The Beaver River system, north and south, along the western margin of the State.

9. The Philadelphia, Wilmington and Baltimore southwest system.

The following tables are arranged in the above order, and will explain themselves :

I. THE PENNSYLVANIA R. R. SYSTEM.

I. Pennsylvania Railroad.

NOTE.-The elevations at the various stations, on the Pennsylvania Railroad, were copied from the Engineers' notes, by permission of Mr. W. H. Wilson, its Consulting Engineer.

The datum, or base of levels, is ordinary high-water in Schuylkill River. This datum, according to Mr. James T. Gardener's determination, is 6.913 feet* above mean surface of the Atlantic Ocean. These 7 feet are added in the second column. Decimal parts of a foot do not occur in these lists. When below .5 they have been omitted; when more than .5 a whole number has been substituted.

*Permanent U. S. Coast Survey granite bench at Gloucester Ferry, N. J., opposite Philadelphia, is 8.10 above Mean Tide Raritan Bay, or Mean Ocean level. Mean Tide Delaware River 8.10- 4,751 — 3.349. Philadelphia City Surveyor's datum: 8.10 -0.632 8.732. Pennsylvania R. R. Engineer's datum: 8.10-1.819 High tide, 6.913.