i-.o 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[May, 



Kai-h of these compnrtnierits having very different eharacteristics, 

 requires a totally different class of works for effecting improve- 

 ments. 



In this short book, Mr. Stevenson limits himself to the con- 

 sideration of the works he has executed witliin the tid.al compart- 

 ment. The volume of the fresh-wator stream is, lie says, a con- 

 stant cpiantity, and cannot be aufrmented by works of art; and, 

 therefore, the engineer must direct his endeavours to produce "an 

 increase in the duration of tidal influence," as the surest means of 

 effecting improvement. 



This he considers may, to a certain extent, be attained in all 

 instances by lowering the bed of the river, and removing all ob- 

 structions to the free flow of the tide, so tliat tlie ]iropagation of 

 the tidal wave may be hastened. This, Mr. Stevenson, from his 

 own e.xperience, shows very satisfactorily may be accomplished. 



The great value of such works is their tendency to increase the 

 backwater, by which the sea channels are kept open, for no works 

 can be of any use which disregard this purpose; neither are they 

 any better, which operate on the seaward compartment without 

 directly operating on the tidal compartment. 



The causes of retardation commonly found in operation are — 

 the winding of the rivers, the slopes of their beds, the downward 

 flow of the fresh water, and the projection of obstacles into the 

 stream, — the latter often the production of engineers. The com- 

 bined effect of these causes is so powerful, that the water is some- 

 times heaped up in the rivers in an extraordinary way, so that in 

 the Dee, Mr. Stevenson found that after the tide had risen 18 feet 

 ■t inches at Flint, it had not begun to flow at Chester, 12 miles up 

 the river. Now, the fall of the bed of the Dee being 11 feet from 

 Chester to Flint, there was therefore a fall at this time of tide of 

 no less than 7 feet 10 inches from Flint to Chester, or a fall up the 

 river. 



A])plying his principles to practice, Mr. Stevenson was able, in 

 the Tay, to get at Perth inland a deptli of 5 feet at low, and 15 

 feet at high water of ordinary spring tides ; instead of, as for- 

 merly, 1 foot 9 inches at low, and 10 feet at high water. He has, 

 therefore, enabled steamers of small draught of water to ply regu- 

 larly at low water from Perth to Dundee, and vessels drawing 14^ 

 feet can now come up to Perth in one tide with ease and safety, 

 instead of grounding or being otherwise obstructed, and losing the 

 tide for Perth, — a misfortune, as he says, which at those times 

 when the tides were falling from springs to neaps, often led to the 

 necessity of lightening the vessel, or keeping her waiting till tlie 

 next springs. The works cost 53,000/., and 841,480 tons of mate- 

 rial were excavated. 



On the nibble, our engineer got an increased tidal range of 

 between three and four feet, and an acceleration of the tidal vvave 

 of about forty minutes, — -so as to make Preston a port, and quad- 

 ruple the tonnage dues. The cost was 40,000/. 



On the Forth, Mr. Stevenson is still at work, with the view of 

 getting ships up to Stirling, and has been successful in his opera- 

 tions so far as he has proceeded. 



Another river on which he is engaged is the Lune, and although 

 the works were only begun in November 1847, he has already de- 

 pressed the level of low water at Lancaster 1 foot 4 inches, accele- 

 rating the spring tides about 25 minutes, and the neap tides about 

 50 minutes, the time of high water remaining the same. There is 

 a gain of an increase of depth of not less than 4 feet in the navi- 

 gation up to the quays at Lancaster. 



The pamphlet which we have named in the heading to this 

 article, discloses a case of great neglect and mismanagement on 

 the part of the River Dee Company, who have not C(unpleted their 

 covenants for imjiroving the river Dee — but rather impaired it, so 

 tliat the trade of Chester is most seriously impeded. The Dee 

 Commissioners, who publish this statement of their case against 

 the Com|)any, are powerless for want of funds, and it is not sur- 

 prising that they advocate handing over the management of the 

 river to the Tidal Harbour Commissioners, — on the principle, we 

 presume, that they cannot be worse oft'; though, from what we 

 have seen of government commissions, there is little good to be 

 hoped from them. 



From the Dee many thousand acres of land might be reclaimed, 

 and the navigation improved, without its costing the country any- 

 tliing more than the temporary advance of tlie funds for the pro- 

 secution of the works : but that river remains in a state which is 

 ruinous to tlie city of Chester, and, to our minds, disgraceful to 

 the engineering science of the country. 



If hydraulic engineering were properly prosecuted as a profes- 

 sional study, we should not find our resources so shamefully ne- 

 glected, nor such a wasteful outlay of the public money in mis- 

 named harbours of refuge, while the country would be adequately 



provided with harbmir accommodation. With a proper adminis- 

 tration, neitlier Fleetwood nor Great Grimsby Wduhi be private 

 works, but would be national enterprises, carried out to afford 

 accommodation to populous and thriving districts. \\ hile, how- 

 ever, hydraulic engineering savours of quackery, the government 

 will be able to carry on theii miserable system of alternate neglect 

 and jobbery. 



REGISTER OF NE'W PATENTS. 



GAS IMPROVEMENTS. 



Alexander Angus Croll, of the Gas-works, Tottenham, Mid- 

 dlesex, for ^'■hrijirovements in the manufacture of gas, and in appa- 

 rntu.f to be 7tned in transmitting gas." — Granted August 22, 1848; 

 Enrolled February 22, 1849. 



The improvements consist, first, in setting retorts and apparatus 

 for making gas from coal. Secondly, for a mode of employing 

 steam passed through highly-heated carbon, and then mixing with 

 carburetted hydrogen as it is distilled from coal. Thirdly, for so 

 employing sulphurous acid gas as to combine with sulphuretted 

 hydrogen gas and to cause the sulphur of the gases to be thrown 

 down or precipitated. Fourthly, for apparatus to he used in 

 transmitting gas. 



It has heretofore been proposed to employ long retorts capable 

 of being fed at each end, and in such manner that tlie jiroducts 

 of gas from the last charge shall pass over the charge which has 

 been for a length of time in the retort, for which purpose each 

 such retort was provided with a rising-pipe at each end, to carry 

 oft" the gas evohed first from one end of the retort, and then at 

 the other, the dift'erent ends of each retort being fed at distant in- 

 tervals, so that the two charges therein will at all times be in a 

 different state of process, one charge being comparatively fresh 

 whilst the other charge will be comparatively spent. 



The first part of Mr. CroU's invention consists of using similar 

 retorts, which can be fed at each end, but in ])lace of having two 

 rising-pipes, one at each end, as heretofore, for carrying off the pro 

 duced gas, he has only one rising-pipe which he applies at one end 

 of a retort, and then, in place of feeding the two ends alternately, 

 and at distant periods one fi'om the other, he charges both ends at 

 the same time, by which arrangement considerable advantage 

 results in the manufacture of gas. 



The second part of the invention has for its object the use of 

 steam passed through carbon at a bright red heat, and then causing 

 it to pass over or amongst the charge of coal which is being dis- 

 tilled in a retort. For this jiurpose he prefers to use retorts as 

 above described, and at the end most distant from the rising-pipe 

 is charged the retorts with coke, and there is a steam-pipe to con- 

 vey steam into the retort at that end, and at the other end of the 

 retort a charge of coal is supplied at every five hours, and steam 

 is allowed to flow in for about the first three hours of each charge. 

 About fifteen gallons of water evaporated and caused to pass into 

 retorts for each ton of coals (that is, when Newcastle coal is used, 

 but when Kennel coal is used the quantity should be increased), 

 produces the most advantageous working, but he does not confine 

 himself to the use of that quantity. The object being to obtain a 

 larger quantity of gas of a fair illuminating power and a less pro- 

 duce tif tar. 



The third part of the invention is for the use of sulphurous acid 

 in such manner as to deprive carburetted hydrogen gas of the 

 sulphuretted hydrogen gas with which it is contaminated, and thus 

 to obtain the sulphur of both compounds in the form of flour of 

 suljihur. 



He first makes a solution of sulphurous acid in water by connect- 

 ing a vessel or vessels of cast-iron (arranged as a \W)ulfe's appa- 

 ratus used for impregnating liquids with gases) with an oven or 

 other suitable apparatus for carrying on the combustion of sulphur; 

 and by means of an air-pump or other arrangement for producing 

 a draught connected with the vessel containing the water or liquid 

 to be impregiuited, a current of sulphurous acid gas from the burn- 

 ing sulphur is made to pass tlu-ough the water or liquid, and by 

 which it is largely absorbed. This is done till the liquid is 

 nearly saturated with sulphurous acid, and to effect this about 

 six ounces of sulphur will require to be burned for every gallon 

 of water. 



The sulphurous acid thus made is transferred to the first of a 

 series of three vessels, (or, it may be, other number of vessels), con- 

 structed and arranged exactly in the same manner as the wet-lime 

 purifiers in common use at gas-works; the other two vessels are 

 charged with a weaker solution, derived after the process has been 



