236 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[August, 



Extract from Mr, Bald's Report read before the General Meeting of the Clyde 

 Trustees, Sept. 3, 1844. 



The improvement of the navigation of the Clyde and the harbour of Glas- 

 gow by deepening is principally due to the labouring force of the steam 

 dredgers, and which is attended with a very considerable annual expense. A 

 question has arisen, whether it might not be possible to work them a longer 

 period of time each day, and perform a greater quantity of work. 



In order to throw some light on this very interesting subject as regards 

 expenditure, the preservation of the depth of the present navigation and its 

 further improvement. It may be first observed that there are five steam 

 dredgers employed in the deepening operations of the harbour and river: 

 their power and depth of working are as follows : — 



No. 1 Bteam dredge has an engine 12 horse power which works in lOi feet depth of water. 

 No. 2 ditto ditto 16 ditto ditto 14 ditto. 



No. 3 ditto ditto 16 ditto ditto 14 ditto. 



No. 4 ditto ditto 20 ditto ditto ISi ditto. 



No. 5 ditto ditto 23 ditto ditto 17 to 19 feet ditto. 



Looking at the small depth of water which these steam dredgers work in, 

 ■with the exception of two of them, and again at the depth in the ship channel 

 of the river Clyde and harbour of Glasgow at high water ; and which fre- 

 quently extends from 15 to 20 feet in depth at lofty tides in gales blowing 

 from south and south-west, it must therefore be manifest that there is a very 

 large portion of time each day in which none of these steam dredges can 

 work, their bucket frames nut being able to reach the bottom, and it must 

 be further observed tliat both the harbour of Glasgow and the river channel 

 of the Clyde are becoming deeper, aad consequently lessening the time of 

 working these dredgers. 



Steam Dredgers — Dimensions of Engines. 



Steamtug, two engines each 30 h. p. ; diameter of cylinder 30 inches; 

 length of stroke 3 feet 9 inches; strokes per minute 40. 



All the steam dredgers have governors which regulate the speed to about 

 28 strokes per minute in ordinary working stulf. 



Average pressure in boilers about 'i\ lb. to the square inch. 



In geneial 14 buckets are discharged per minute. 



The speed of the buckets on the frames in Noa. 1, 2, 3 and 4, is (3 ft. 

 5 J in. X 14 = 48 ft. 5 in.) 48 feet 5 inches per minute. 



And No. 5 is (3 ft. 8 in. x 14 =49 ft. 8 in.) 49 feet 8 inches per minute. 



The larger the engine the less is the consumption of fuel on board the 

 dredgers. The small engines are worked to their full power, and consequently 

 consume more fuel in proportion to their power tlian tlie larger engines, 

 which are not so much pressed; for example. No. 1 consumes about 18 lb. of 

 coal per horse power per hour ; while No. 5 only consumes 15| lb. per horse 

 power per hour. 



Details of the Working Operations of Deepening and Cleansing the river 

 Clyde and the harbour of Glasgow. 



Year ending 25th December, 1841 

 Year ending 24tb December, 1842 

 Year ending 23rd December, 1843 

 Year ending 2ist December, 1844 



11.841 18 2 



13,612 11 3 



9.742 7 6J 



10,659 3 8 



Quantity of 



Work 

 Executed. 



Cubic Yards. 

 218,110 

 3i3,810 

 294,440 . 

 317,660 



8 



The expense of dredging and depositing the material taken up from the 

 bed of the river Clyde and the liarbour ol Glasgow varies considerably, on 

 account of the nature of the material in the bottom and the distance it has 

 to be carried for deposition. 



A puut load may be taken at an average at about 10 cubic yards. 



Value of Machinery employed on the river Clyde. 



5 deepening machines with engines and gearing . . 20 000 



Steam tug, with tivo engines each 30 h. p 3,300 



l.')7 punts 12,.'ill0 



13 putits for stones . . . . . . . . . . . . 650 



2 diving-bells .. .. .. .. .. .. 750 



Fifteen additional iron puDts amount to about .. 2,025 



Tutil Jf6'j;lii 



IMPROVEMENT OF THE RIVER SEINE. 



The Chamhrt de Commerce at Rouen being anxious to remove ob- 

 structions iu the navigation of the Seine, from that city to the sea 

 ports of Havre and Honfleur, addressed a letter of enquiry to Mr. Bald, 

 the engineer for the improvement of the Clyde. The following ex- 

 tracts from his letters have been obligingly communicated to us, and 

 afford interesting information on this important subject. 



Extracts from a part of Mr. Bald's correspondtnce on the improve- 

 ment of a portion of the Seine, addressed to tin President of the Chamber 

 of Commerce of Ruuen, 1845. 



"I have seen your river Seine, but it is 19 years ago, and I have 

 not been in France since 1831 ; but, neveitheless, rending your letter 

 carefully over, I can readily understand what your objects are. 



"All the celebrated engineers of this country, — Smeaton, Rennie, 

 Telford, Nimino, &c., have all concurred in opinion that the improve- 

 ment of tidal rivers for navigable purposes depends upon obtaining a 

 greater flow and a greater quantity of tidal water upwards into them. 

 Now, this principle being admitted, it is manifest that all obstructions 

 to the tidal flow upwards should be removed, such as shoals, bars, &c. ; 

 and that all means should be adopted to increase the quantity of tidal 

 water into all the higher and upper reaches of tidal rivers. This will 

 give a greater scouring power to keep the navigable channel free 

 from shoals; but it may also considerably deepen and improve it. 

 Besides, if there are any bars or shoals at the mouth of a tidal river, 

 their removal can best be achieved by obtaining and procuring a 

 larger quantity of additional tidal water up into the higher reaches of 

 the river. 



" Now, you state that it is proposed to deepen the river Seine by 

 contracting its banks, and to prevent the water of the river from 

 spreading so widely as it used to do; and that this operation is to be 

 limited at first to the upper part of the river, alvvays.allowing the free 

 course of the tide, &c. 



" I really do not see how you can contract the banks of any river so 

 as to prevent the water spreading, without in some measure inter- 

 cepting the tidal flow. I siiould be wanting in duty if I did not warn 

 you, on no account to give the least obslruclion to the tidal waters 

 upwards by narrowing the banks of the river, by the construction of 

 dykes. To achieve this important object requires much careful con- 

 sideration and great reflection in the execution of the works ; because, 

 if you shall in any measure diminish the tidal flow upwards into the 

 highest recesses of the Seine, you will lessen your tidal scour out- 

 wards, and in all likelihood diminish the depth of water at the moulh 

 of vour river, and also at your ports of Havre and Honfleur. My ad- 

 vice is, to try and carry the tidal waters as high up as possible into 

 the upper recesses of the Seine, and to be cautious and careful how 

 you narrow the river. I am not able to convey to you all my ideas 

 regarding this great and important improvement for France ; because 

 1 am not in possession of many details connected with the speed and 

 volumes of the fresh and salt water ascending and descending, the na- 

 ture of the bottom, soil, tides, &c. &c. ; nor am I in possession of any 

 detailed plans to enable me to arrive at anything definite on this in- 

 teresting subject; but, nevertheless, I am strongly impressed wah the 

 idea, from my recollection of the Seine, that a great improvement 

 could be efl'ected as regards its navigation. 



"I am not able to refer you to any river in Europe where so much 

 has been done as in the Clyde in improving a tidal river navigation ; 

 in ]7o5 the river Clyde could only float vessels drawing three feet six 

 inches of water; now the river Clyde can float vessels drawing 18 feet 

 of water, notwithstanding the many errors which have been committed 

 in improving it during the ninety years it has been under the hands of 

 the engineer. And 1 really do not see why you should not, with care 

 and attention in the construction of works, attain a depth of 20 feet of 

 water instead of 10 or 12, as you mention ; and that fleets ol both mer- 

 chantmen and also of-men-of-war should be able to obtain perlect 

 shelter and security within the embouchure of the river Seme. 



"I again take the liberty to caution you that any works which shall 

 be proposed for the deepening of the navigation of the Seine should 

 be carefully considered, because a great deal has been done on this 

 river Clyde which must be undone at a great expense ; errors of the 

 gravest kind have been committed, notvMthstanding the great success 

 in deepening it, and this depth is now only preserved by an annual 

 dredging of about 180,000 cubic yards of deposit on a riv er line of 18 

 milts long. Now the great object should be to get the iiUai Scour, to 

 preserve the depth, and sure this great annual exptHititure ; therefore 

 the operations of nature should everywhere be assisted in deepeimig 

 by the aid of works which have been fouud to be successful." 

 a Monsieur J. Rondtauz, President of the Chamber 

 of Commerce at Roai.ii. 



