98 | THE HAMILTON ASSOCIATION. 
In 1824, Lohrman, of Dresden, proposed to issue in twenty- 
five sections a lunar map 36% inches to the moon’s diameter ; but, 
his sight failing, only four sections were printed. As Lohrman was 
a professional surveyor, and was assisted by the astronomer Encke, 
and used one of the celebrated telescopes made by Frauenhofer, of 
Munich, his work had rare merit, and is still referred to. 
In 1834-6 appeared the map of the moon, by Beer and Meedler. 
It was on a scale of 3 ft. 2 in. to the moon’s diameter, and was fol- 
lowed the next year by their great explanatory work—Der Mond ; 
oder allgemeine vergleichende Selenography. Their labors carried 
lunar investigation far beyond the most advanced stages reached by 
their predecessors. Their book of more than 4o0 closely-printed 
pages, for exhaustive descriptions, and their map for minute details, 
won them unstinted praise, and still command the highest esteem. 
Later workers in their field of labor have employed more powerful 
instruments and made out details they failed to record, but their 
drawings and descriptions are still standards of authority, and are 
likely to remain such. Their mode of working shows the value of 
their work. ‘To fix ninety-two chief points on the moon’s disk, as 
bases for further measurements, they made nearly a thousand 
micrometric measurements from the limb of the moon. They 
also measured one hundred and forty-eight lunar formations with the 
micrometer. They made one thousand and ninety-five measure- 
ments of the shadows thrown by eight hundred and thirty different 
lunar mountains, minutely noting particulars of illumination at each 
measurement. From the length of these shadows the height of each 
mountain was carefully computed, and the resultant heights served 
as standards for determining the elevation of minor peaks whose 
shadows were projected under like conditions of illumination. They 
named one hundred and fifty lunar formations not named before, 
but made no innovations on the accepted nomenclature except that 
in carrying out Schrceter’s plan of designating un-named craters by 
Greek and Roman letters they used Greek letters only for elevations, 
lower-case Roman letters for depressions, and Roman capitals for 
measured points. Their telescope was a Frauenhofer refractor of 
834 in. aperture, having a magnifying power ranging from one hun- 
dred and forty to three hundred diameters. ‘They worked chiefly 
with an aperture of 41% in., and did not often use so high a power 
