156 M. Baker—Surveys and Maps, District of Columbia. 
occupied or unclaimed land. Under this provision the General 
Land Office acted as the local land office for the District of 
Columbia, and whenever vacancies were discovered and reported 
a request for survey was presented. A deposit of three shillings 
and six pence per acre, Maryland money, was required, and an 
additional charge of four shillings was afterward required to 
complete the purchase, which thus cost the purchaser seven 
shillings and six pence, or one dollar, per acre. It is interesting 
to note that under this law the General Land Office has received 
applications for and has made surveys of about 60 tracts in the 
District of Columbia. Perhaps the most noteworthy case was 
that of the Kidwell bottoms, or Potomac flats, as we now call 
them. 
The Boschke Maps.—Albert Boschke was a German employed 
in the Coast Survey before the war. He conceived the idea of 
making a very accurate map of Washington and of the District 
of Columbia, with the hope of selling to the Government. 
He was at the time employed in the drawing division of the 
Coast Survey, and while so employed organized a corps of sur- 
veyors at his own expense to do the fieldwork. This gradually 
absorbed his time and thought, led to irregular attendance at the 
office, and finally to his enforced resignation from the survey. 
Two maps resulted from his work, one a map of the whole 
District, the other a map of the city. The map of the District 
is usually spoken of as the Boschke map. It was engraved upon 
copper by Mr David McClelland, and was just about to be pub- 
lished—indeed, a few copies or proofs had been printed—when, 
the war breaking out, the Government seized the map and plates. 
The map of the city was produced first and published in 1857. 
It is interesting from the fact that the houses were drawn from 
actual tape-line measures in the field and drawn with scrupulous 
painstaking. It is also interesting as being one of the early 
pieces of work of the well-known firm of lithographers, Bien & 
Company, of New York. . 
The field-work of the District map was based primarily upon 
a line from the dome of the Capitol to the Naval Observatory. 
The data was taken from the Coast Survey Report for 1851, and 
the position of the observatory as there given was assumed by 
Boschke to refer to the transit circle. 
It subsequently appeared that it referred to the station on the 
roof from which angles had been measured, and his base line 
