160 A. Guyot on the Appalachian Mountain System. 
idea of the normal proportions of the system in all its parts. 
Meanwhile I present the list of results already obtained, hoping 
that this preliminary publication will afford some interest to sci- 
entific men, At the same time I desire to have it considered as 
a resumé merely of special memoirs in whic shall give the 
original measurements, and shall indicate the details of the work 
and the method employed for deducing these results. It is my 
wish to do my part toward establishing an usage which should 
be invariable among men of science, to give the elements on 
which are based the results, which should be in the common 
treasure of our knowledge. This would furnish to sound criti- 
cism the means of determining their proper value. In this par- 
ticular case, however, such details may be more fitly placed 
in the transactions of scientific societies. 
a 
observers themselves. At another time I may offer some further 
remarks upon this subject. At present I will only add thatthe 
value of the coéfficients in the formula of Laplace must be slightly 
modified, in accordance with the more recent determinations of 
the physical data which it employs, and that the corrections 
which depend upon the temperature and the hour of the day in 
which the observations are made, deserve a much closer degree 
of attention than has hitherto been accorded to them. 
In the volume of Physical and Meteorological Tables, pub- 
lished by the Smithsonian Institution, I have mentioned two 
instances in which my barometric measurements were followed 
the next year by leveling with a spirit level. This occu 
the two culminating points of the Appalachian system, Mount 
Washington in the White Mountains of New Hampshire, and the 
summit of the Black Mountains in North Carolina. The received 
height of Mount Washington had previously been 6226 feet. 
measurements in 1851 gave 6291 feet. e€ measurements 
spirit level, by U. A. Godwin, Civil Engineer, in 1852, gave ¢ 
feet, and a similar leveling under the direction ¢ 
vey in 1853, gave a height of 6293 feet. 
