516 Trans. Acad. Sei: of St. Louis. 
Barometric Determination. A station of the U.S. Signal 
Service (Weather Bureau since 1891) was established in the 
building of the Experiment Station on the University grounds 
in Columbia during the summer of 1889, and observations were 
commenced on August 21st. Since that time observations have 
been regularly made each day at 7 p. m. central time, simulta- 
neously with observations made at the other meteorological sta- 
tions in this region. The yearly means of observations of the 
barometer and thermometer furnish data for the determination 
of differences of height. Through the kindness of the officers 
of the Weather Bureau I have been furnished with the monthly 
means of the readings of the barometer and the attached and 
external thermometers during the period September Ist, 1889, 
to September Ist, 1893, for the stations at Columbia, St. 
Louis and Kansas City, Mo. Using Laplace’s formula for 
the purpose as given in the Mechanique Celeste, I have 
computed the difference of elevation between the barometer 
at Columbia and those at Kansas City and St. Louis for each 
one of the 48 months. The observations at Columbia and St. 
Louis give the height of the Columbia barometer above sea 
level as 779 feet. The observations at Columbia and Kansas 
City give 776 feet, and the mean, 777.5 feet, is adopted. 
The Observatory Bench Mark is 38.3 feet lower than the 
Columbia barometer, which gives as the height above sea level 
of the Observatory Bench Mark 739 feet. 
Results of Spirit Levels. In June, 1893, the Board of 
Curators of this University appropriated a sum of money for 
the purpose of running a line of levels from the Observatory 
to a bench mark of the Missouri River Commission located in 
the town of Providence, about nine miles distant. In the © 
report of the Mo. Riv. Com. for 1890, page 3396, this bench 
mark is designated as B. M. 354 and its height above the St. 
Louis Directrix is given as 181.523 feet. More precise levels 
which have since been run indicate a correction to this value 
of +0.141 ft. and we adopt, as the height above the St. 
Louis Directrix of B. M. 354, 181.664 feet. The work of 
running these levels was intrusted to two of my students, 
Messrs. F, B. Williams and W. L. McCrary. The instrument 
used is a good wye level belonging to the University. The 
