Engineer's office of the Blue Ridge Railroad
Sepr. 1st. 1854
To the Board of Public Works
The appearance of the cholera among the Irish at the main tunnel, suspended, as a natural consequence, in a great measure, operations on that work. This mysterious disease was first developed on the east side, where it carried off, as near as I could ascertain, 25 victims out of probably 150 individuals; it then left this side altogether and passed over the mountain, where the hands immediately dispersed, not until however it had carried off 8 more of their number. During the prevalence of the epidemic, I succeeded in keeping the pumps in operation: the cholera has proceeded westwardly and the neighbourhood of the tunnel is now perfectly healthy, and the work has been resumed on both sides, though not with a full complement as yet. It is remarkable that, on the equally exposed work of Mr. Kelly, where upwards of One hundred hands are employed, whose habits are exactly the same, not one case of the disease has occurred, though it seems to have marked the Irish especially for its prey.
As may be expected, under such circumstances, very little progress has been made, though more than I had supposed. Some little timbering remains yet to be raised, beyond which the rock, though not sound enough to be considered safe without arching, will require no temporary support; so that we shall have hereafter very probably to attend only to excavation, though for a while of enlarged dimensions: the eastern excavation continues as hard and stubborn as heretofore.
Kelly's embankment is an almost interminable job, which settles nearly as fast as it is raised; the track over it has already been raised a great many times; but I have, under your instructions, considered this part the duty of the Central r. road co., and its agents have attended to it regularly.
The Brooksville Tunnel is the most difficult work of the kind, I have seen any record of: at the Western entrance, the pressure of the big slides actually causes the bottom to surge up, as is sometime the case in coal mines; in view of the sliding tendency and immense pressure of this ground, it will be advisable to enter on that side with an invested arch to prevent a collapse.
Yet, this is, by no means, the greater difficulty of this work: in the middle, right under the apex of the ridge, the roof keeps falling down in large disintegrated masses, as stated in my last communication, which has induced me to adopt a particular plan of framing to pass through the avalanche, without the necessity of removing the whole; which might be endless, and so dangerous that the men would certainly decline going on with the removal of the fallen mass after having passed the edge of it; for, it is impossible to specify from what height the materials are now falling. This work is vastly more difficult than the Greenwood Tunnel was, though it was not, by any means, an easy safe job.
I make these remarks as an introduction to what I have to say in regard to the bricks made by Mr. Dettor. When we constructed the Greenwood Tunnel, we had to select bricks from his kilns, as well as from Harris's & Walker's: we experienced some loss from the necessity of pressing so dangerous a work, while mixed bricks were delivered to us, many of which could not be used.
But here we have a position contract, which Mr. Dettor has insisted to fill and a work which requires the best of bricks; for, the arch, at the bad place above described, must be made strong enough, not only to resist great pressure, but also the fall of rocks from a considerable height. Now, under your resolution at the last meeting, I have estimated the probable number of admissible bricks at 750 thousands; But Mr. Dettor goes as high as 1,400 thousands, nearly double; and well may he do so, if he continue to deliver such bricks as he insists upon sending.
He has lately made some very good bricks; but his former kilns were generally inferior; and I do not think that any competent judge would receive, for such a work, over the above number of 750 thousands. The case may be hard for Mr. Dettor, whose contract was made when prices were much lower than now; but the safety of travelers and of trains, and the interest of the commonwealth in the permanency of the work, are paramount considerations, which alone I have a right to consider. — To yourselves, gentlemen, I refer the matter as the only competent tribunal to regulate it.
Mr. Dettor's clay is certainly not the best in the neighbourhood; where, I know, better bricks can be made: we can probably use some of his present bricks, not included in the 750 thousands, in the abutments, in the face of the portal and in the invert; but still a great many more must be rejected than he contemplates; and, if he continue his contract on the same spot, I fear that he will increase his losses, unless I were guilty of dereliction of duty, & to move his yard would subject him to additional expense.
Under these circumstances, all I can suggest is to make a new contract for chosen bricks especially for this important arch. This contract could not be executed until spring; but, it would not interfere much with the progress of the arch, as the big slide will not allow of that side being entered with the arch much before that period; and we have enough to do until then in overcoming the middle crumbling section with proper timbering.
If it were your pleasure, in view of some of the hardships of Dettor's contract the new price for arch-bricks might be allowed him for such of his as may be admitted into the arch.
If so authorized by you, I will proceed immediately to advertise for such a contract as here suggested; this arch is too important to be deterred by the additional cost the measure will involve — the number of superior bricks required would be about 300 thousands; the contract, however, might be for 600 in order to allow of a safe choice, and the additional cost not over $1,300.
We have already completed about 70 ft of the arch at the eastern side; but there the pressure is inconsiderable; and yet we found some difficulty in the selection of suitable bricks, among those delivered. Resp. Submitted
Chf. Engn. B. r. r. rd.
All Rights Reserved
William G. Thomas