ISIS."] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



10* 



COAL DROPS, AND MIDDLESBOROUGH DOCK. 



C With Engravings, Plate VI. J 



Account of the Drops used for the shipment of Coals at Middleshro'- 

 on-Tees, with a description of the Middlesbro' Dock. By George 

 Tup.NBULL, M. Inst. C. E. — (From a paper read at the Institution 

 of Civil Engineers.) 



Tlie (lock was commenced in the spring of 1810, and was opened 

 for trade on the 12th May, 1812. The general form of the dock 

 and its position with respect to the river Tets will best be under- 

 stood by reference to the annexed engraving. It possesses an area 

 of 9 acres at the water surface ; the appr lach is by an entrance 

 channel, rather more than a quarter of a mile in length, cut 

 through the sand banks of the river, and kept open by means of 

 occasional sluicing from the lock-gates, and also through culverts 

 built in the lock walls for that purpose. Some apprehensions were 

 entertained of the practicability of keeping open the entrance 

 channel by these means, as there is much shifting sand in the bed 

 of the river Tees, and every interference with the current of the 

 river produces marked alterations in the form and position of the 

 shoals or sand banks. After due deliberation, the scheme was at 

 length carried into execution, under the sanction of the Tees 

 Navigation Company, and the result has been marked with the 

 complete success which was anticipated by the projectors ; the 

 channel was dredged out to its full depth, the slopes and banks 

 were covered with a paving of rough chalk and stone, and after a 

 trial of nearly three years the channel is now in a better state 

 than when it was first made, and is kept up at a very trifling cost. 



The entrance lock is built principally on a foundation of hard 

 sand, and on account of the quantity of water found in it, an un- 

 usually large proportion of piling and wooden platforms were re- 

 quired in the foundations. The lock is built of stone, chiefly from 

 the Byker quarries, on the river Tyne ; it is 132 feet long and 30 

 feet wide ; the depth of water is 15 feet at neap tides and 19 feet 

 at spring tides : the bottom of the dock was excavated to the 

 depth of 3 feet under the level of the lock cills. 



In connection with the dock, a branch line was laid down, di- 

 verging from the Stockton and Darlington Railway and terminat- 

 ing in ten double lines, leading to the ten drops (1 to 10) situated 

 on the west side of the dock. The raised platform of a triangular 

 shape, covered by these diverging lines of railway, comprises an 

 area of 15 acres, and affords spare room for 1,200 loaded wagons, 

 or more than 3,000 tons of coal, besides means of egress for the 

 locomotives with their trains of empty wagons. This great 

 amount of standing room forms a principal feature in the arrange- 

 ment of these works, as in the district, of which this is the shipping 

 port, there ai-e numerous descriptions of coal, several of which 

 come down the railway in the same train ; a separation is made on 

 the platform, and each colliery having its own drop assigned to it, 

 the wagons, with the proper description of coal, accumulate in one 

 branch, and descending along the railway, which is so inclined as 

 to permit the wagons to move by their own gravity, the shipment 

 is carried on with much facility. An inclination in the contrary di- 

 rection is given to the empty line, sufficient to allow the unloaded 

 wagons to move of themselves, by which means some saving of 

 horse labour is efl^ected. 



The cost of all the works connected with the dock, including 

 the branch railway, raised platform, permanent rails, dock work, 

 entrance lock and channel, and breastworks along the shore of tlie 

 river Tees, with the ten coal drops, amounted to the sum of 

 £122,000. 



These works were designed by Mr. W. Cubitt, V. P., and the 

 author was the acting or resident engineer. 



The coal drops are peculiar in their construction and are pro- 

 bably not much known beyond the district in which they are used; 

 they are distinguished from the drops in common use on the Tyne, 

 by the coal wagons being lowered perpendicularly to the ships' 

 decks, whereas in the latter the wagons are lowered by means of a 

 cradle and vibrating frame, which describes the arc of a circle in 

 its descent. In places where the wagons have to be lowered from 

 a height of 30 feet and upwards to the ships' decks, which is a 

 common circumstance in the Tyne and the Wear, the vibrating 

 frame (originally invented by the late William Chapman of New- 

 castle) are found well adapted for the purpose ; but where the 

 height is limited, or where the railway is so low that the wagons 

 are just clear of the taft'rail of the light ships, the perpendicular 

 drop becomes more convenient. This ingenious contrivance was 

 first suggested to the Clarence Railway Company by Mr. George 

 Leather, of Leeds (M. Inst. C. E.), and was carried into efl'ect at 



Xi 



