This tubing was made of galvanized iron plates, riveted together and soldered; at the top of the hole it was in three concentric circles, which had been screwed and forced down successively until an obstacle was met with at three different places. So soon as the outer circle reached the first depth, all hope appears to have vanished, from those who bored the earlier part of the work, of getting the tube farther; a second tube was, therefore, inserted, which seems to have advanced as far as the second obstacle, where it, in its turn, was abandoned; and a third one advanced until it rested in the strata at the lower part of the lias freestone of a blue nature, as found on the rocks at Seaton Carew, and in the bed of the Leven, near Hutton Rudby. The diameter of the first tubing was 37⁄8 inches external and 31⁄2 inches internal; the second tube was 31⁄4 inches external, and 3 inches internal diameter; and the third tube was 23⁄4 inches external and 21⁄2 inches internal diameter.

Such being the account gathered from the workmen who superintended the earlier part of the boring, it became necessary to decide upon the best cause to remedy the evil. At first sight it would have appeared easy enough to have caught the lower end of the tubes by means of a fish-head properly contrived, and thus to have lifted them out of the hole, and replaced them with a perfect tube, such as a gas-tube, with faucet screw-joints; but, on attempting this, it soon became evident that however good the tubing which might have been adopted, it would be a work of the greatest difficulty to extract when once it was regularly fixed and jammed into its place by the tenacious clayey strata surrounding it; and the difficulty of extracting it, in the present case, was even enhanced by the inferior quality and make of the tubing; in short, that, unless by crumpling it up in such a manner as to destroy the hole, it was impossible to extract this tubing by main force.

There was, therefore, no other choice left but to attempt cutting it out, inch by inch; though before doing so, force was applied to the bottom of the tubing, to the extent of upwards of 30 tons, the only result being the loss of several pieces of steel down the hole, which had to be brought up with a powerful magnet.

After much mature consideration and contrivance, it was determined to order such tubing as would at the same time present as little obstacle as possible to the clay to be passed through on the outside, as well as surround the largest of the three tubes then in the hole, and present no obstacle to their being withdrawn through its interior.

These tubes were made 12 feet in length, flush outside and in, the lower portion being steeled for 6 inches from the bottom end, so as to cut its way and follow down the space, and cover that exposed by the old tubes when cut and drawn, as shown in [Fig. 92].

In order to commence operations, and avoid too much clay going down to the bottom of the hole, a straw-plug was firmly fixed in the lias portion of the hole. The lower portion of the new tubes was then screwed around the old ones by means of powerful clamps, attached to the exterior in such a manner as to avoid injuring the surface; and when they could be screwed no farther, the knife or cutter, [Figs. 92 to 94], was introduced inside the old tubing. Some force was needed to get this knife down into the tubing, but the spring a giving so as to accommodate itself to the hole, permitted its descent to the distance required; this being effected, it was turned round so that the steel cutter, shown at b, being forced against the sides of the tube, cut it through in the course of ten minutes or a quarter of an hour’s turning. See section at b, c, [Fig. 93].

Figs. 92-94.

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