168 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[May, 



iioco and Ainnznii'" (tlie frosli water from these rivers being 

 traced at a distaiii-c of 2()i) and '.MO miles from tlie lajid), and also 

 observations bv Mr. A. Stevenson on tbe Cromarty Firtb, where 

 the velocity of the under current, at the dejjth of 50 feet, was 

 ascertaineil to be at least double the velocity at the surface. The 

 de]>tbs of water on tbe bars of tbe .Mersey anil Dee, Mr. Stevenson 

 stated, were only about 11 feet at low water of spring tides — on 

 the Kibble about 7 — the Lune about 6 — and the Tayal)outl6; 

 and in naviijatin^ such estuaries, ve.ssels must wait for the proper 

 time of tide, either to leave ov enter them. It would readily oc- 

 cur, therefore, that tlie maintenance of the depth of water over the 

 bar was of vital imjiortance to all ports situated within tidal estua- 

 ries. Kroni a careful investif;;ation of such localities, he thought 

 it might fairly be stated, that, so long as tbe ca])acity of the re- 

 reiving basins remained entire, no fear need be apprehended of a 

 decrease of water on the bar; and this view he was the more in- 

 clined to believe to be correct, from tbe circumstance that, in seve- 

 ral cases where be had occasion to compare the present state of some 

 navigations with their condition as represented in tbe early charts 

 of Mackenzie, the celebrated marine-surveyor, made upwards of 

 half-a-century ago, he had found, that although the forms of the 

 sand-banks and the direction of the navigable channel might have 

 slightly changed, still there was no appreciable alteration in the 

 depth of water on the bars; while, on the other hand, it had been 

 ]iretty well established, particularly in the cases of Rye in Susse.v, 

 Soiithwold in Suffolk, and of Chester on the river Dee, and other 

 places, that much injury had been caused by the embanking of 

 land.'i 



The interests of proprietors of land along our rivers and estua- 

 ries, were often at variance with those of the conservators of navi- 

 gation; and the endeavours made in many instances to protect and 

 reclaim land were calculated, from being injudiciously and too ex- 

 tensively carried out, to be highly prejudicial, and hence arose the 

 obvious necessity for some board of appeal between the interests of 

 proprietors and those of the public — a power which was vested in 

 the Lords Commissioners of the Admiralty, to whom, as c jnserva- 

 tors of navigation, we were indebted for the preservation of many 

 of our harbours auil tidal rivers. So important indeed was this 

 subject considered, that, on the motion of Mr. Hume, the govern- 

 ment, in 1811, appointed a Tidal llarbciur Ciuumission, to inquire 

 into the state and condition of the harbours, shores, and navigable 

 rivers of the L'nited Kingdom, and to report wliat injury might 

 have been done by encroachments or other interference with tidal 

 waters; and, without detaining the Society longer, he thought he 

 would best illustrate what is generally acknowledged to be the cor- 

 rect theory on this subject, by quoting the conclusion stated in the 

 first report of that commission, whicb is as follows: — That " as a 

 general, although not a universal principle, no cause has operated 

 more extensively to injure the entrances of harbours throughout 

 the United Kingdom than excluding the tidal waters from lands 

 below the level of high water, which served as natural reservoirs 

 for the flood tide, and were the means of affording a valuable 

 scouring power during the ebb. Nor does any subject more deserve 

 the vigilant attention of your Majesty's Government, or of those 

 entrusted with the conservancy of our harbours, than such en- 

 croachments, which are usu.iUy made (juietly and gradually, and 

 when once completed, are difficult afterwards to remove." 



lo Kl Maratiam y Aniivzi>na9. Madrid, IfiS-l.— Sabine's Account of Experiments to 

 di'turinine the lignre or" tlie Karth. Ltnduo, 1825, j). 44-'). 



1 1 Reports of Tidal Harbour Commission. —Kennie's Reports on Hydraulics to the 

 DriLish Association. 



small cylinder, having at its lower end a projecting-]iiece, which 

 is bolted to the side i, of the boiler; through this projecting-piece 

 two passages c, i>, are formed, leading into the pipes c', </'!, which 

 terminate respectively at the upper and lower parts of the boiler; 

 and the passages c, d, are provided with cocks ir, D-. /, is an over- 

 flow or waste-pipe, for carrying off all excess of water from the 

 cylinder fl;—;/j is a cock for discharging all the water from the 

 cylinder a, when desired; y. is an hydrometer, the graduated stem 

 of which works through a hole in a fixed guide It; and /, is a ther- 

 mometer. 



RCGISTSa OP NEW PATENTS. 



A SALINOMETER. 



AnmifiKw Peddik How, of the United Si 'ss, but now residing 

 in Basinghall-street, city of London, engine r, for "«« instrument 

 (If iiistruiHCiits Jhr ascurtditiiii;/ tlii'. xultni'jis of mater in bai/rrK." — 

 (iranted July 18, 184-9; Knrolied .lannary 18J 18J0. [Reported in 

 \fwti/H's Ijimdon Journal.^ 



The subject of this invention is an instrument called by the 

 [latentee a salinometer, by means of which the engineer is enabled 

 to ascertain, at all times and under all circumstances, the density 

 and consecpiently the saltness of the water in tlie boilers of marine 

 steam-engines, independently of the pressure within the boiler. 



Fig. 1, is a vertical section of the salinometer; and fig. 2, is 

 another vertical section, taken at right angles to lig. 1. «, is a 



Fig. 2. Fig. 1. 



The action of the instrument is as follows: — Either the cock <P, 

 or the cock rf-, is left open (according as it may be desired to test 

 the density of the water at the upper or lower part of the boiler), 

 and the water passes from the boiler through the passage c, or d, 

 into the cylinder a, and is discharged therefrom through the o\er- 

 flow or waste-pipe /; so that there is a constant flow of water 

 through the salinometer of the same density as the water in that 

 part of tbe boiler from which the supply is derived; and this den- 

 sity is ascertained by examining the graduations on the stem of 

 the hydrometer. If the water, which is passing through the 

 instrument, is derived from the upper part of the boiler, and it is 

 desired to te.st the density of the water in the lower part thereof, 

 the cock (■-, is to be closed and the cock D-, opened; then the water 

 frimi the lower part of the boiler will quickly drive out of the 

 cylinder a (through the overflow or discharge-pipe), all the water 

 tliat had previously entered from tbe upper part of the boiler; and 

 the water which flows through the cylinder o, will then be of the 

 same density as the water in tlie lower jiart of the boiler. 



A thermometer is combined with the instrument, because the 

 density or saltness of the water varies with the degree of tempera- 

 ture, and it is necessary to correct the indications of the hydro- 

 meter by those of the thermometer, as often as the temperature 

 rises or falls beyond the standard point to which the hydrometer 

 may have been graduated. Thus, supjiosing the hydrometer to 

 have been graduated on the assumption of the water being at a 



uniform temperature of 200' Fahr., and that Pr, represents the 



density of the water at tliat temperature, the patentee finds that 

 for every increase of 10" in the temperature of the water, one- 

 eighth of a degree, or thereabouts, must be deducted from the 

 amount of density indicated by the hydrometer; and for every 

 decrease of 10", one-eighth of a degree, or thereabouts, must be 

 ailded. For example, if the temperature is increased to 210°, a 



■>0 



deduction of one-eighth must be made on that account, from the^V,' 

 which will bring the density to —; or if the temperature is lowered 

 to 180°, an addition of two-eighths must be made, which will make 

 the corrected density "-f,- 



