No. 50.] 
327 
position of that plateau which forms the base of, and extends west of 
the Adirondack mountains. From the want of time and the requisite 
angular instruments I was obliged to have recourse exclusively to baro- 
metrical measurements. 
The instruments used at the two stations were Bunten's mountain 
barometers, purchased by the University of Vermont, with special re- 
ference to their adaptedness to exact observations. These instruments 
are syphons, with the bores of the two legs made scrupulously equal ; 
thus avoiding erroneous corrections for capillarity. The zero point is 
near the middle of the scale, and the readings are from that point to 
the tangents of the two mercurial surfaces. The sum of these gives 
the observed length of the column. Such is the construction of the 
vernier that it must be careless reading which would give an error of 
five hundredths of a millimetre, or about two thousandths of an inch. 
The thermometer attached is encased in the brass scale which sur- 
rounds the tube at its middle. The graduation of both the thermome- 
ter and barometer scale is very accurate. A great variety of compara- 
tive observations which I have made in connexion with Prof. G. 
Benedict leaves no reasonable doubt of the accuracy of the graduation 
or uniformity of the tubes. 
Of the observations made at Burlington to synchronize with those at 
the superior stations, those before the 6th of July were made by Prof. 
G. W. Benedict, whose high standard of accuracy is well known. 
The elevation of this station is 235 feet above Lake Champlain, as de- 
termined and verified by the spirit level, or 325 feet above tide, es- 
timating the elevation of Lake Champlain at 90 feet. The observa- 
tions at Burlington, after the first of August, were made by my brother, 
whose carefulness and skill in observing had been tested The eleva- 
tion of this station above tide v/as 374 feet, determined by the spirit 
level as above. 
The table below exhibits the notes as they were taken from the in- 
struments, with their respective calculated elevations. To convey a 
just idea of the agreement or discrepancy of the results, I have present- 
ed all that were made, with the exception, I think, of five or six, some 
of which bore evident marks of faiiltiness in their observations. The 
two numbers in the sixth column, corresponding to each date, are the 
upper and lower readings of the barometer, which are recorded instead 
of their sum, as furnishing a means of verifying the accuracy of the 
