1910, the line from Cairo, Ill., to Memphis, Tenn. (230), was rerun, thus completing the releveling from Cairo, Ill., to the Gulf of Mexico.

The results of the releveling makes the Cairo datum 20.434 feet below the adopted mean Gulf level at Biloxi, Miss., and makes the Memphis datum 6.630 feet below the same mean Gulf level. This shows a discrepancy between the earlier and later lines of precise levels of 0.508 foot at Cairo, and 1.182 feet at Memphis. The discrepancies seem to increase irregularly until Greenville is reached, and then decrease irregularly. The discrepancy from Memphis to Cairo is 0.674 foot, or slightly greater than the total discrepancy between the terminal points, Biloxi and Cairo as shown above.

The discrepancies along the line of levels are very irregular, as indicated in the table given below, but as it is proposed to submit a separate memorandum on the discrepancies between the earlier and later leveling the subject will be only briefly referred to here.

The earlier levels were run in part by the Comstock survey, in part by the U. S. Coast and Goedetic Survey and in part by the Mississippi River Commission.

The leveling, however, was all done by the Mississippi River Commission, and as the methods have been much improved since the earlier leveling was done, it has been tentatively decided to accept the releveling as correct.

The following are discrepancies between the two lines of levels at some of the principal points along the Mississippi River on the line from Biloxi to Cairo:

P. B. M. XXXIX.

800

+1.003

-0.179

Helena, Ark.

P. B. M. Helena II.

306

+0.776

-0.405

Austin, Miss.

P. B. M. Austin I.

289

+ 1.012

-0.170

Memphis, Tenn.

P. B. M. Memphis '03.

230

+1.160

-0.022

Memphis, Tenn.

P. B. M. 3 (Nicol 1876).

230

+1.191*

+0.009

Memphis, Tenn.

P. B. M. 4 (Nicol 1876)

230

+1.196

+0.014

P. B. M. 43

175

+ 0.937

-0.245

Eight Miles below Cottonwood Point, Mo..

Three Miles below Columbus, Ky.

The above table indicates that if the later line of levels is accepted as correct, the elevation on the published detail charts of the Mississippi River Commission south of Cairo are in error by quantities varying from 0.0 to 1.1 feet, depending on the locality.

It is assumed for the present that the leveling northward of Cairo is correct. The error in elevations on the published charts of the Commission north of Cairo, Ill., is therefore 0.674 foot. That is, to reduce elevations published on detail charts of the Commission north of Cairo to latest value of Memphis datum, subtract 0.674 foot.

To reduce elevations of published detail charts of the Commission north of Cairo to finally adopted mean Gulf level, subtract 7.304 feet.

To reduce elevations on published charts of the Commission south of Cairo to Memphis datum, no constant correction can be given for reasons before stated.

On November 15, 1911, the Commission decided to refer elevations of surveys to the Memphis datum, and directed that provision be made for "putting, at each permanent benchmark on the map, both its elevation above Memphis datum and above mean Gulf level."

From what has been said before, however, it is evident that the Memphis datum elevations on the new maps will not agree with Memphis datum elevations on the old maps, and will not be directly comparable with them, until the old maps are corrected.

As an argument in favor of using only the mean Gulf level, it might be stated that the U. S. Coast and Geodetic Survey, after full investigation of the tidal records of the Commission, concluded to adopt the Commission value of mean Gulf level and has used it since, and in the general adjustment of the great continental level net published by Coast Survey in 1903 and 1907, elevations are all referred to mean sea level, which is assumed to be the same in the Atlantic and the Gulf of Mexico. The U. S. Geological Survey accepts this Coast Survey adjustment and publish elevations referred to Sea level, as does the U. S. Lake Survey, so that at the present time the most ex

tensive surveys of the country are using a common datum, that is mean Sea level. The U. S. Weather Bureau also refers ele

vations to Sea level.

The former published values for Cairo and Memphis below preliminary value of mean Gulf level were:

Datum planes referred to finally adopted mean Gulf levels.

CONCLUSION: The elevations of all precise level benchmarks of the Commission are now to be referred to the adopted mean Gulf level by resolution of the Commission.

The elevations of all gage zeros are now published by this office referred to adopted mean Gulf level.

The U. S. Coast and Geodetic Survey and other extensive U. S. surveys refer all elevations to this sea level datum, which will undoubtedly be the future reference plane of all general surveys of the United States and of all the great railroads. By resolution of the Commission of November 15, 1911, "The surveys will be referred to the Memphis datum"

(This especially refers to the resurvey below Cairo.) The published charts of the Mississippi River Commission refer elevations to Memphis datum, using of course, the earlier levels, but the writer does not know of any resolution of the Commission prior to that of 1911, just quoted, directing the use of the Memphis datum.

MINUTES OF MEETINGS AND BUSINESS OF THE SOCIETY.

Regular Meeting of the Board of Direction, October 13, 1919.

The meeting was called to order with President Olsen in the chair and the following members present: Messrs. Lawes, Klorer, Burwell, Moses, Robert. Messrs. Riess and Williamson came in later. The minutes of the previous meeting were read and approved. The ballots for new members were then opened, there being 67 ballots. As a result the following members were elected to the respective grades of membership:

Resident Members.-W. H. Davidson, Elliott J. Dent, Charles A. Favrot, Andrew Wm. Jackman, James R. Lowe, Irving H. Morse.

Non-Resident Member.-John L. Henning.

Transfer from Junior to Resident Member.-Ralph Earl.
Associate Member.-Edmund J. Glenny.

Junior Member.-Emile C. Freeland.

Transfer from Student to Junior.-Henry Hester Bate, Joseph W.

Joachim.

Upon application of Mr. Frank Reynolds, his status was changed from Resident to Non-Resident, and the status of Mr. E. H. Coleman was changed from Non-Resident to Resident, both as of October 1st, 1919.

A letter from Professor Anderson, the Editor of the Proceedings, requesting an appropriation of $15.00 per month for office assistance in preparing the Proceedings. His request was granted.

The financial report of the Secretary was read and received and bills ordered paid.

Upon motion, the matter pertaining to the American Society of Engineers was ordered printed in the Journal so that the membership might get acquainted with the proposition before deciding on the affiliation with the same.

There being no further business, the meeting adjourned.

J. M. ROBERT, Secretary.

Regular Meeting of the Society, October 13, 1919.

The meeting was called to order with President Olsen in the chair and 72 members and guests present. The minutes of the previous meeting were read and approved. Mr. Klorer made a brief statement concerning our affiliation with the American Association of Engineers.

The resolution of Major W. B. Gregory was passed to the second read

ing. The resolution was read as follows:

"Resolved, That the Louisiana Engineering Society endorses Senate Bill 2232 to create a Department of Public Works, and that this endorsement be forwarded to the two Louisiana Senators and our Representatives in Congress."'