LIST OF UNPUBLISHED ATLAS SHEETS IN THE STATE OF MARYLAND.1

1 The surveys for these sheets have been completed and the maps will be published at an early date.

LIST OF PUBLISHED GEOLOGIC FOLIOS IN THE STATE OF MARYLAND.2

2 The Geologic Folios can be obtained at the price of 25 cents a folio by addressing The State Geologist, Baltimore, Md., or The Director U. S. Geological Survey, Washington, D. C. The location of the Folios is shown upon the accompanying map.

OPERATIONS OF THE UNITED STATES COAST AND GEODETIC SURVEY IN

MARYLAND."

The following memoranda relative to the history of the United States Coast and Geodetic Survey operations in the state of Maryland, giving dates of triangulation, successive charts, etc., are herewith presented.

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3 Prepared under the direction of the Superintendent of the U. S. Coast and Geodetic Survey.

SURVEYS OF BALTIMORE AND VICINITY.

In the early years of the United States Coast and Geodetic Survey a topographic survey of Baltimore and vicinity, incidental to that of the state of Maryland, became a subject of interest. A letter of Professor Hassler, the first Superintendent of the Coast Survey, date of January 7, 1834, to the Secretary of the Treasury, remarks: "It is proper for me to get more information upon the views of the survey of a map of the state of Maryland upon which Professor Ducatel had corresponded with me last summer." He writes under date of January 9: "In the course of last summer, Professor D. informed me that he and Mr. Alexander had been appointed by the Legislature of Maryland to make a topographical map of the state and its junction with the Coast Survey."

In April, 1834, Professor Hassler, in another letter to the Secretary of the Treasury, writes: "Upon your favor of the 9th, relative to the junction of the survey of Maryland with the Coast Survey, authorizing me to make the proper arrangement to put the measure into execution, I shall make the appropriate agreement with Messrs. Ducatel and Alexander, combine with them and then give you details upon the plans agreed upon mutually."

Three months later Mr. Hassler reports to the Secretary the indefinite postponement of the proposed work, the Maryland committee not being ready to perform its part.

A period of ten years then elapses before any steps were taken for surveys in Baltimore or the Patapsco river.

Professor Hassler had in the meantime been succeeded by Professor A. D. Bache.

December 23, 1844, in report of Professor Bache, mention is made of the beginning of the secondary triangulation in the Patapsco river under the direction of Assistant F. H. Gerdes. The triangulation in the near vicinity of Baltimore was done by Assistant Ferguson, who determined the positions "Rosanne," five miles from the centre of the city, near the old Frederick road, and "Finley," several miles farther. in a northeasterly direction. These points were important factors in

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1 Washington Monument was also determined during the same period.

the several triangulations made in after years. Hydrographic work had not yet been begun. Topographical surveys were in progress in charge of Assistant Geo. D. Wise, at the entrance of the Patapsco river.

In his report of December, 1845, Professor Bache states: "Materials for a chart of the Patapsco river and Baltimore harbor will, it is confidently expected, be ready for use this winter, and the chart will at once be drawn and put in the hands of the engraver. The topography has been executed by Assistants Gerdes, Hassler, Wise and Cutts. Sheets Nos. 6 and 8 are completed, and on No. 9 considerable progress made. No. 8 includes Baltimore City and adjacent country." Referring to sheet No. 8, Mr. Wise remarks: "Having found it impossible to reconcile the measured distance with printed plan of the city (Poppleton's map presumably), it was found necessary to make a detailed survey, especially of the part near the water."

During 1845 the hydrography of the Patapsco river and Baltimore harbor was begun and completed. Topographical work was continued in the same localities during this year and 1846.

In 1847 engraving of the chart of the localities above named was begun.

In 1848 magnetic observations were made at Fort McHenry. Report of Professor Bache, December 27th, states: "Map of Baltimore harbor and Patapsco river still in hands of engravers."

"During the year a verification' of the topography of the city of Baltimore was made by Assistant J. B. Gluck."

Report of November 5th, 1851, mentions: "Map of Baltimore harbor, etc., still in hands of engravers."

During 1853 Assistant H. L. Whiting was engaged in verification of topography of the Patapsco shores.

1854, a re-survey of the Patapsco river entrance was made by request of the Engineer Department, U. S. A.; no considerable changes were developed. With this the record of field operations by the Coast Survey in the vicinity of Baltimore, prior to the Civil War, closes.

In July, 1863, by request of the military authorities at Baltimore,

1 These verifications were in reality re-surveys.

a topographical survey of the city and its approaches was begun. The triangulation, in charge of Sub-Assistant C. H. Boyd, based upon such data as could be availed of or discovered (the primary and secondary points of the work of 1844), was extended over the area designated. The points determined by Assistant Boyd included the following objects, whose identification at the present time is quite possible: "House of Refuge," "Mt. de Sales," "Druid Hill," "Greenmount Cemetery," "St. John's," "Baltimore Cemetery," "Pious " (Rives Hill), and "Clifton." The topography was begun at the same time by Aid J. W. Donn. It was designated that the area of the survey should be limited to a circuit of four miles, with the Battle monument as the centre. The triangulation was completed during the summer and the topography advanced to the south along the principal roads. J. W. Donn was succeeded by C. T. Iardella in this work in October. C. M. Bache was also assigned to a part of the survey in January, 1864. C. M. Bache advanced the work from Jones' Falls westward to a junction with the initial survey of J. W. Donn, while C. T. Iardella proceeded eastward of the Falls to Cross Keys village. C. M. Bache finished his work in September, having covered an area of 20.5 square miles. C. T. Iardella continued his work until the middle of 1865, the last part of it upon the south side of the Patapsco. The area surveyed was 30 square miles.

HYDROGRAPHIC SURVEY Of the BrancHES OF THE LOWER PATAPSCO. -During the early summer of 1869 the following branches of the Patapsco river were surveyed by Assistant J. W. Donn: Curtis creek and its branches, Stony creek and its branches, Rock creek, Bodkin creek and its branches-all on the west side—and Bear creek and its branches, North Point and Welshman's creek on the east side.

TRIANGULATION OF 1866.-This work, by Assistant F. P. Webber, was carried over the Patapsco river from the entrance at Seven-foot Knoll to the city. One point, "Washington Monument," distant from the river and within the city limits, was included in his scheme. The points in his work were generally useful in harbor and river resurveys, and comprise the following, many of which entered into succeeding schemes: "Monument," " Bayview Asylum," "Fort Mc