148 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[Ma' 



be cntrprcssfd into the Bniallest practicable space, still so as at the same 

 time ti) gi\(; the greatest power: in order to elFect this, tuliular boilers of 

 the most improved construction and power of evaporation ; direct acting en- 

 gines, in which wrought iron is substituted for cast iron whenever it is prac- 

 ticable, Hsine sufficient steam of a greater densin, together with ample 

 stowage for fuel to last for the average probable time that steam power may 

 be required, luust be used. I5y the judicious comhiiiation of steam witli 

 sailing, the time of long voyages may be materially reduced, and at tlie 

 sauic time considerable saving may he etfected in the transport of mer- 

 chandise. 



The Electrical Telegraph. 



Connected with, and forming a most important adjunct to, the locomotive 

 system of communication, njay be mentioned that extraordinary and useful 

 invention, the Electrical Telegraph. 



The invention consists in directing a current of electricity through a wire 

 or a seriis of wires connecting together the intended points of communica- 

 tion. The galvanic or electric current may be produced, either by a battery 

 or by employing the natural electric currents of the earth. The telegraph is 

 worked by handles, which act by means of galvanism upon needles attached 

 to the wires at the other end of the telegraphic line, through which the gal- 

 vanic current is conveyed, and deflects them to points on a dial-plate, having 

 symbols (according to Cook and Wheatstone's system) or letters or numbers 

 to represent the intelligence to be communicated. By this means intelli- 

 gence is conveyed from one point to another along the line of wires, almost 

 as soon as conceived, and thus, independent of the advantage as a means of 

 conveying intelligence from one point to another unconnected with the rail- 

 way, it is of great importance in the working of the railway itself, by pre 

 venting accidents ; or in the event of an accident unfortunately occurring, 

 enabling assistance to be despatched without loss of time to remedy the evil 

 and clear the obstruction. Several persons claim the merit of this invaluable 

 invention ; it is difficult to decide with accuracy upon the claims of priority ; 

 like most other inventions, however, it has been perfected by degrees, and 

 each party is entitled to his due share of credit. About the year 1819, Mr. 

 Ronalds, of Hammersmith, is staled to have applied electricity for the pur- 

 pose of effecting telegraphic communication, and succeeded so far as to com- 

 plete a current through eight miles of wire. He also employed electricity as 

 a means of communicating motion to a series of wheels. This apparatus, 

 however, was too imperfect to be of much use, but it is evident, that the 

 idea once propounded and partially carried into effect, to a certain extent, 

 establishes Mr. Ronald's claim to the merit of the discovery. In 1830, M. 

 Ampere pointed out the means of deflecting magnetic needles by a current 

 of voltaic electricity, for the purposes of telegraphic communication, and the 

 principles of this discovery have, it is said, been applied to many of the mo- 

 dern electrical telegraphs. The first plan employed was so very complicated, 

 and so liable to get out of order, that it was soon abandoned ; but Wheat- 

 stone and Cook so completely improved upon it as almost to make it a new 

 invention. Their system consisted of a dial-plate with symbols, to which 

 the deflected needles pointed, when moved by electric agency. At first it 

 was considered that it was necessary that the wires for conducting the cur- 

 rent of electricity should be kept entirely isolated in iron pipes ; subsequently, 

 however, this was found to be unnecessary. They are now stretched be- 

 tween a seiies of posts placed at given intervals apart, beside the railway, 

 and a dial apparatus is placed at most of the principal stations, as well as at 

 the termini. '1 be first telegraphic line upon Wheatstone's plan was estab- 

 lished, in the year 1839, upon the Great Western Railway, between London 

 and Sluugh, a di.^tance of 18 miles, and since that time it has been so much 

 imjiroved that it is now generally adopted. It is already complete on the 

 South Western Line between London and Portsmouth, and is being laid 

 down on the North Western and on numenuis other lines. 



A company, called the Electrical Telegraph Company, has been formed for 

 carrying cut the plans proposed by Wheatstone, to whom great credit is due 

 for the perseverance and ability with which he has worked out bis system. 

 Bain also claims a right to the invention, and, in addition to the means of 

 electrical telegraphic communication, has invented a mode of jirinting by it 

 at the same time, thus atTording the means of secrecy, and preventing mis- 

 takes; for the apparatus being kept locked in a room or box, no one can 

 have access to it but the person to whom the communication is made. Other 

 modifications of the system have been introduced, but hitherto without being 

 extensively employed. 



Another vaUiable application of electricity to engineering operations con- 

 sists in blasting rock and other materials above and under water. The first 

 effective application of this principle to blasting, may be said to be due to 

 General I'asley, who employed it for blowing up the wreck of the ' Uoynl 

 George,' sunk at Spithead, in the year 1782, and which, by its own bulk as 

 well as the aUuvial deposit accumulated round it, formed a serious obstiuc- 

 tion in that important roadstead. Pasley, at the request of the .\dmiraity, 

 undertook to remove it, and commenced his operations on the 29th August, 

 1839, by sending down divers, in order to ascertain the exact state and posi- 

 tion of the wreck; having done this, he proceeded to place powerful charges 

 of gunpowder in water-tight tin cases in those parts ol the vessel where they 

 would have most effect, and they were exploded by an electrical current con- 

 veyed through them, by means of wires attached to them, and connected 

 with a voltaic battery placed in a boat floating near : the explosions were in- 

 stantaneous and almost unfailing, and a great effect v\as produced : in this 

 manner he succeeded perfectly iu removing the wreck in about two sum- 



mers. The same system was afterwards pursued, in removing the wreck of 

 a vessel in the Tliames, and is now generally adopted in similar circuni- 

 stances. It was applied by Cuhitt, at Round Down Cliff, for the purpo,-e of 

 removing a large mass of the cliff on the line of the South Eastern Railway, 

 between Hover and Folkestone : the portion operated upon was several 

 hundred feet long, and between 200 and 300 feet high ; the charge of powder 

 c^insisted of 18,000 lb., disposed in several cells in the line of the intended 

 explosion, and properly tamped with sand : the explosion took place on tha 

 28tli J.muary, I8l3, and was perfectly successful, removing about 250,000 

 cubic yards of chalk rock ; its success was of great importance to the railway 

 operations, inasmuch as it materially expedited them, and considerably re- 

 duced the cost of this difficult portion of the line. This method of blasting 

 upon a great scale is now generally adopted, and enlarges the sphere of ope- 

 ration in this department of civil engineering, as well as in the removal of 

 rocks uiuler water ; for which it was used by Rennie many years since. A 

 very successful application of gunpowder, for facilitating engineering opera- 

 tions, has recently occurred in the removal of a number of marl rock slioali 

 in the bed of the River Severn, executed by Edwards, for Gris=ell and Pcto, 

 under \V. Cuhitt. Martin Roberts also lays claims to the invention ; he ex- 

 hibited his experiments at the Craig Leith Quarries, in March, 1839. 



Thompson has proposed to effect the blasting, or rather the ignition of the 

 powder, by means of common electricity, produced by an apparatus enclosed 

 in an air-tight box, so as to prevent the admission of moisture ; this appa- 

 ratus is said to be more simple and less expensive than the galvanic bat- 

 tery. 



Clocks. 



Connected with the correct working of the railway system, nothing is more 

 important than accurate time-keepers ; for upon these depend the regular 

 starting and arrival of the trains, so that one train may not interfere with 

 the other, and collisions be prevented. 



The introduction of clocks into Great Britain took place about the year 

 1288, and, in 1326, Wallingford is said to have constructed a clock regulated 

 by a balance, which was put in motion hy weights, but whose action was 

 extremely irregular. The great improvement of the pendulum does not ap- 

 pear to have taken place until about the middle of the 17th century, and the 

 name of the person who first employed it for this purpose is not accurately 

 ascertained. About 1G41 Richard Harris is said to have constructed a pen- 

 dulum clock for St. Paul's church, Covent-garden ; however, as lluygens, in 

 1658, was the first who explained accurately the motion of the pendulum, 

 the chief merit of its application to clocks may be attributed to him. The ap- 

 plication of the spiral spring to the balance is due to Hooke in 1(J58; and 

 the introduction of the compensating mercurial pendulum by Graham, in 

 1715, was the next great step in improvement; by means of this valuable 

 invention, the unequal expansion and contraction of the pendulum from 

 change of temperature, which rendered impracticable the accurate measure- 

 ment of time, was obviated. Graham also suggested the idea of employing 

 different metals, having different properties of expansion, so that the one 

 should neutralise the other ; his idea was afterwards carried out by Harri- 

 son, in the construction of the gridiron pendulum. For the going fusee, tha 

 compensation curb, and other improvements, he received a Parliamentary 

 reward. 



The scapement, which communicates the sustaining force to the pendulum 

 or balance, demands the greatest skill and accuracy, and various forms have 

 been attempted; amongst others may be mentioned the original scapement- 

 wheel, with its teeth at right angles to the plane of the wheel ; the anchor 

 scapement, invented by Clement in 1680 ; w hich was improved by Graham, 

 so as to render it more isochronous ; the duplex scapement, which does not 

 require such extreme accuracy in the teeth, whilst at the same time it per- 

 forms equally well: the detached scapement, by means of which the teeth 

 of the scape-wheel always rest on a detent, except when it is unlocked to 

 impel the pallets, is employed in chronometers where great accuracy is re- 

 quired ; these, and many other improvements, too numerous to mention, are 

 worthy of notice. 



The art of clock or watchmaking, termed horology, may be said to be 

 principally composed of four parts. 1. The moving power, which is gene- 

 rally a weight for clucks or fixed time-keepers, and a spring for watches or 

 moveable time-keepers; in the former case, the line suspending the weight 

 should be equal throughout its calibre, and the cylinder on which it is coiled 

 should be true; iu the latter case, the form of the spring should be such that 

 its force may act as equable as possible. 2. The scapement, which com- 

 municates the sustaining force to the pendulum or balance: the construction 

 of this demands great skill ; there are various kinds, the common crown 

 wheel, the anchor, the duplex, the detached. Sic. 3. The means of com- 

 municating the power to the niiuuie, seconds, and hour hands, which is 

 effected by a series of wheels nicely proportioned and adjusted to each other, 

 having many of the axes or ceutres working upon diamonds or rubies, to re- 

 duce the friction and diminish the application of oil, which is objectionable 

 on account of its being acted upon by the temperature. 4. The regulator, 

 which is effected by a pendulum in clucks and hy a balance in watches. The 

 striking (being merely a secondary part), is easily effected, when the other 

 great poiuts have been determined. The perfection of the art consists in the 

 proper proportions, adjustmeut, and adaptation of the various parts to each 

 other, and the combinaliun of the several improvements above descrihed ; 

 this has now been so completely attained that time can be marked so as not 

 to vary the fraction of a secuud in a day : for these important and valuable 



