1877.] 19 
(Carll. 
We now have these figures, using the decimals for Union Depot, Oi} 
City. 
By levels onateio, Kitt: bench... <6. 809.94 + 199.20 —0.45 = 1008.69 
‘** Old levels ie Soe Rr ae sic, ofan 809.94 + 198.00 — 0.45 = 1007.49 
SOMES Miedd barker 8 DepOt. .26.- .o. + cies se aie .889.4 + 118.90 = 1008.30 
It seems safe therefore to accept 1008’ as the established elevation of this 
point. 
Our levels thus adjusted to Oil City, the next step was to connect the 
termini of the several Railroads centering there, with the Union Depot. 
When this was done the following rather discouraging results appeared : 
iWnion Depotiaccepted: elevation, 2...) 0m siecre - <ciene «ore 1008/ 
ap fos DY Bevers Ot OC. (Gi NE) Raises s:< 6 995/ 
ue sree sae | SON he or UW Sy ERG: Gaaccl steish ose. 1007/ 
* ST les so) Sounded UCR = ister | eg = aed cera ee ae” LOLI 
The 0. C. & A. R. levels appear to agree with the P. & E. and were sup- 
posed to be based on the P. R. R. datum at Philadelphia, which required 
an addition of 7’ to reduce it to ocean and make it conform to Lake Erie at 
573/ above ocean. The A. & G. W. and L. 8. & M. S. levels came in 
direct from Lake Erie. There was evidently some error between Oil City 
and the Lakeif our accepted elevation of the Union Depot was correct. We 
endeavored to find it by connecting together the several Depots and bench- 
marks obtained from the railroad profiles, at Franklin, Irvineton, Corry, 
Union City and Erie, but did not succeed, and finally as a last resort, re- 
leveled the P. & E. R. R. from Union City to its junction with the L. 8. & 
M.S. at Erie, and to the Lake. 
To our surprise, the profile of the P. & E., which had been considered 
unreliable, was found to be remarkably correct, except as to ocean datum. 
The stations checked closely in every case, except in one or two instances 
where no doubt there had been an alteration of track, and the difference of 
elevation between Union City and the crossing at Erie as given by it and 
as ascertained by our levels varied only 0.08’. 
By connecting the P. & E. Depot at Union City with the A. & G. W. 
Depot at the same place it was found that these two roads gave precisely 
the same fall from Cory crossing to Union, so that it was not deemed neces- 
sary to re-level that part of the P. & E. Rail Road. 
From the Erie crossing above mentioned, connection was made with the 
L. $8. & M. 8. Depot at Erie, and, also, a line was run direct to the Lake. 
The line to the Lake confirmed the elevation given by the L. 8. & M. 5S. 
R. R. for the Depot at Erie. It showed about six inches less elevation, 
but this is probably due to full water in the lake at this season of the year. 
The P. & E. levels may therefore be considered as well tested and 
checked from the lake to Corry crossing, and they establish the latter 
point as will be seen further on at 1427/ above ocean (at New York). 
When we inquire into the reason why 1416/ was given on the old P. & 
