284 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Sept. 



cuuni becomes greater; and is the great deduction to be compared with the 

 loss of power under the locomotive system — {Stephenson.) 



The leakage on the Dalkey line between the piston and the valve raust be 

 caused by had joints to the tube — (Field.) The amount of leakage on a sec- 

 tion of three miles wouhl not be greter than that on tlie whole Dalkey line, 

 because the tube would he better made with elastic joints — (Brunei.) 



On the Dalkey line the leakages of the air-pump and of the connecting 

 tube are much greater than they need he. The leakage of ilie air-pump and 

 connecting tube is greater than the laakage of the main — {Robinson.) 



A very large proportion of the leakage takes place, not in the connecting 

 pipe, but in the pump itself — (Stephenson.) 



As the leakage on the Dalkey line arises from defective mechanical con- 

 trivances, it is possible, but not probable, that in the progress improvements 

 this loss may be materially diminished — (Stephenson.) 



(To be continued.) 



HARBOURS OF REFUGE. 

 Abstract of the Report of the Commissioners. 



The more immediate points for the consideration of the Commissioners 

 appear to be tlte following : — 



1st. Whether it be desirable that a Harbour of Refuge should be con- 

 structed in the Channel, reference being had, on the one hand, to the public 

 advantages likely to result from the construction of such a work, and, on the 

 other, to the expense to be incurred in its completion. 



2ndly. What site would be the most eligible for such a harbour, on ac- 

 count of its combining in the greatest degree the following grounds of pre- 

 ference : — 



1st. That it should be of easy access at all times of the tide to vessels re- 

 quiring shelter from stress of weather. 



2ndlv. Tliat it should he calculated for a station for armed vessels of war 

 in the event of hostilities, both for the purposes of offence and defence ; and, 



3rdlv. That it should possess facilities for ensuring its defence in the event 

 of an attack by the enemy. 



We invited the Chairman of Lloyd's and the Chairman of the Ship Owner's 

 Society to meet us, or to delegate others, to state the opinions of those great 

 mercantile bodies, witli reference to the positions they consider best as ports 

 for the slielter of the trade. 



We have also bad before us every class of persons who were thought 

 capable of affording information, including several eminent engineers; and, 

 in order to guard against the often misleading opinions of residents at the 

 ditferent ports, we have examined many others, practically acquainted with 

 the various places, whom we believed to be unbiassed by local partialities, 



Dover. 



History affords proof of the importance attached to this place as a military 

 and naval station. 



As the advanced post of England on the south-east coast, the want of a 

 harbour here of sufficient capacity for the reception of vessels of war, and for 

 the convenience and protection of trade, has attracted the notice of sove- 

 reigns and ministers from the earliest times, and has led to a large expendi- 

 ture of money for the improvement of the present tidal harbour. 



In considering positions eligible for the construction of breakwaters, it 

 should be borne in mind that an inner harbour is an indispensable requisite, 

 and if there is no natural advantage of that sort in the position selected, 

 there must be the double operation of building an inner as well as an outer 

 harbour. 



There are few places that in this respect possess greater advantages than 

 Dover. It has a dry dock for repairs, and extensive quays, with storehouses. 

 Besides the outer receiving harbour, there is a basin covering more than six 

 acres (now being enlarged to double that size), and a third called the Pent, 

 which the late Mr. Kennie, in his report to Mr. Pitt, in 1802, says, may of 

 itself be made capable of receiving many sloops-of-war and gun-brigs, and 

 which the Dover Commissioners are now considerably improving. 



Mr. Pitt, when Lord Warden of the Cinque Ports, was earnestly intent on 

 having Dover Bay enclosed, and it was this circumstance which led to our 

 obtaining from the Master-General of the Ordnance the plan of a harbour in 

 Dover Bay, by the late Major-General Ford, of the Royal Engineers. 



There are two points, each of great importance, which have been sug- 

 gested as objections to any proposal for converting Dover Bay into a harbour ; 

 one that the holding ground is not good, the other that it will have a ten- 

 dency to silt up. 



With respect to the quality of the anchoring ground. Her Majesty's steam- 

 vessel, the Blazer, of 500 tons and 120 horse power, was ordered there to 

 test its tenacity to the utmost. The nature of the experiments and the satis- 

 factory result will be seen in Captain Washington's Report in the Appendix. 



In reference to the question of silting up, the Commission directed sam- 

 ples of the water in Dover Bay to be taken up at different times of tide, in 

 different depths, and under varying circunisiances of weather, which have 

 been transmitted to the Director of the Museum of Economic Geology for 



examination ; the results, as reported by Mr. Phillips, will he found in the 

 Appendix. 



■Tbe Commission is of opinion that more extensive experiments are neces- 

 sary in order to determine the quantities of matter borne in suspension by 

 the tidal currents on this part of tbe coast and liable to deposit, and beg 

 therefore to suggest to your Lordships the propriety of their being continued, 

 under tbe ditection of tbe Admiralty, for the space of a year, in all circum- 

 stances of weather. 



Dover, situated at a distance of only four miles and a half from tbe Good- 

 win Sands, and slandhig out favourably to protect the navigation of the nar- 

 row seas, is naturally the situation for a squadron of ships of war. Its value 

 in a military point of view is undoubted ; but tbe construction of a Harbour 

 of Refuge there, is, in our opinion, indispensable, to give to Dover that effi- 

 ciency as a naval station which is necessary in order to provide for the secu- 

 rity of this part of the coast, and tbe protection of trade. 



Beachij Head, East Bourne, and Seaford. 



We have now to draw your Lordships' attention to the bay on the east 

 side of Beachy Head, and westward of Langley point, which the commission 

 of 1840 proposed as a site for a breakwater. 



On the west side of Beachy Head tbe anchorage is free from the dangers 

 which render the east side less eligible as a place for constructing a harbour 

 of refuge. The holding ground off Seaford is of the best quality, and is much 

 resorted to in easterly gales. 



The Commission are of opinion that there is no good position in the neigh- 

 bourhood of Beachy Head, where a harbour is as necessary as in any part of 

 the channel, (being about half way between Dover and Portsmouth,) except 

 in Seaford Road. 



The Commission are fully aware of the objections which may be made to 

 the formation of a breakwater harbour on the west side of Beachy Head, 

 considering the prevalence of the westerly wind ; but the local disadvantages 

 on the east side of the Head, induce them to give a decided preference to the 

 west side, and the proximity of Newhaven has materially influenced their 

 decision. 



Portland and Weymouth. 



Our last visit westward was to Portland, which, from its situation with 

 reference to the Channel Islands, and as tbe boundary of the narrow part of 

 the Channel in this direction, came naturally within the range of our investi- 

 gation. 



A squadron stationed at Portland will have under Its protection, jointly 

 with Dartmouth, all the intervening coast, and these places, with Plymouth, 

 will complete the chain of communication and co-operation between Dover 

 and Falmouth, a distance of 300 miles. 



There is everything at Portland to render the construction of a breakwater 

 easy, cheap, atid expeditious, and tbe holding-ground in the road is particu- 

 larly good. A large part of the island facing the hay is Crown property, and 

 contains abundance of stone. It has numerous springs, and plenty of the 

 best water may be led in any direction for the supply of ships. 



Haneich Harbour. 



M'e have now to submit to your Lordships a few observations respecting 

 llarnicb Harbour, which we consider one of very great importance to the 

 trade of the country. 



This harbour, formed by the junction of tbe rivers Stour and Orwell, is 

 one of the finest, and may be rendered one of the most useful havens in the 

 kingdom. It has a sufficient depth of water and good holding ground over 

 an extent capable of containing many hundred ships. 



But with the exception of a channel, of 18 feet in depth, too narrow fof 

 general purposes, the entrance to this port is not deep enough to adujit ships 

 of more than 12 feet draught of water at low. water spring tides ; it is there- 

 fore at present a tidal harbour as regards ships of a larger class. 



It is remarkably well situated for the convenience of a North Sea squadron^ 

 and for the protection of the mouth of the Thames. 



It is the only safe harbour along this coast, and is in the direct line of 

 traffic between tbe Thames and the northern ports of the kingdom, as well 

 as of the trade from the north of Europe. 



There is a dock-yard with budding slips belonging to the Crown, and the 

 property under the Ordnance department is extensive. 



It appears in evidence that by the falling away of Beacon Cliff, on the 

 west side of the entrance, and the lengthening out of Lanilguard Point, on 

 the east side, the harbour has sustained great damage within the last 25 

 years. 



The bottom at the entrance to the harbour, and the coast on each side, is 

 composed of blue or London clay, in which are layers of " cement stone," in 

 great demand both in England and on tbe Continent. Hundreds of bands 

 are constantly engaged in collecting it, and the evidence snows that by ex- 

 cavating the cement stone in front of the Ordnance premises, near the foot 

 of Beacon Cliff, the water has spread so as to he diverted from its natural 

 course, and the tide rendered so comparatively feeble, that it no longer acts 

 with its accustomed force on Landguard Point, which has consequently 

 grown out 500 yards during the past 40 years, as shown by the plan. It has 

 already neatly filled up the deep-water channel, and, by its further increase, 

 threatens to destroy the entrance. 



In the Appendix there are Reports to the Admiralty from the officer 

 carrying on the surveying service in the neighbourhood of Harwich, to wbieh 



