Carll.] 20 [May 4, 
E. profile as the elevation of the old Corry depot, and A. & G. W. crossing, 
instead of 1427 as it should be; we find that the levels of this end of the 
road, as far eastas Warren (how much farther we do not know) were run 
from the Lake. They were based on lake level at 565’, the accepted eleva- 
tion of the lake at the date of that Survey, and were consequently 8’ too 
low. In addition to this there seems to have been an error in placing the 
old P. & E. Lake Depot 8/ above the surface of the Lake. It should have 
been 11’asthe levels now show. It appears quite probable that this 3’ error 
in starting at the lake was discovered and corrected in some of the engi- 
neers’ notes, for I have a copy of the levels from Irvineton, west, procured 
from the Smithsonian Institution in which the Stations are all raised 3/ 
above Burgin’s profile. This 3/ error added to the 8/ difference between 
former and present accepted lake level, makes the 11’ which we are obliged 
to add to raise the road to its proper height above the ocean and to place it 
in its true horizon to meet the levels brought up from Pittsburgh. 
The first elevation given on the P. & E. profile as published (crossing 
of the L. 8. & M. 8. R. R.) shows very plainly that there is an error of 11’ 
between that point and the Lake thus : 
IS) ike MSS.ccrossing by P. dz Ki. protile (VIED) == 676 
e a it SONS 7.coe MLS pronles CX) 68i 
i ue ie “* Carll’s levels to lake = 687 
As the levels and checks above mentioned appear to establish the correct- 
ness of the P. & E. profile from the Erie crossing to Corry we see no rea- 
son to doubt its integrity as far as the same parties carried forward their 
ine, which we are informed by one who assisted in the Survey, was as far 
as Warren. We therefore propose to raise all the stations between the 
Lake and Warren 11’. 
We now find that the Union and Titusville or O. C. & A. R. R. R. (a) 
must be raised 13’ at Union City above the published levels to lift it to the 
P.& E. at that place, and 13/ also at the other end at Irvineton to make it 
coincide there with the P. & E. This brings Oil City up also and makes 
it agree (995/ + 13/ = 1008’) with our accepted elevation, as will be shown 
further on. 
Another interesting fact is brought to light by this discussion. The lev- 
els of the O. C. & A. R. R. were run from a datum given in the field book 
as ‘‘ Elevation of track on bridge east of Irvineton Station on P. & E. R. R. 
above tide water at west end of Market Street bridge at Philadelphia = 
1160.”’ 
This is, no doubt, the point given by Burgin as “Irvine 1162” and it 
explains why (having started 2’ too low) the O, C. & A. R. R. requires to 
be raised 13’, while the P. & E. is only raised 11’. It also shows that the 
O. C. & A. R. R. datum was not the P. R. R. datum as supposed, but ocean 
datum, based on-Lake Erie at 565’, subject to the same error of 11’ as the 
P. & E. with the additional 2’ made in the starting point at the bridge. 
(a) The U. & T. is now a branch of the 0. C. & A. R. R. R. 
