Show efrom JF ro rom m the montreal transcript an 11 li tee THE VICTORIA BRIDGE ACROSS THE ST LAWRENCE T th the work for the construction of this noble edifice is is now rapidly proceeding and we nad tad rad a an n 0 opportunity ap pp or a few days ago ago 0 of examining not only t the h completed parts of the structure but alsot h operations which are taking place on the dams and pers piers which are not yet finished we first proceeded over the abutment on the north ellore shore to the tubes which are already placed across the two first spans of the bridge the work of the riveting ot the plates was going on and the structure rang with the cino cin clangor o r of hammers forming the beads heads of the boi boj bolts boits A large number of portable forges were ivere stationed in all parts of the tube tubs and on the top of ft it and rivets heated in the bres fires d to the yvor kyor kmen by boys attending in r on each forge it is interesting 1 to see the speed with which iron a material materi 1 hardly known a a few aw years ago in the he arts of construction can he formed into edifices adapted to the ilg ill purposes po by s of oi man this speed is much facilitated cilita ted tid by the circumstance that all the he parts odthe tubes are multiplications of the same patterns the brid bridge bride e will consist of twenty four piers with twe twenty nt y five openings t or the cen ter about half as large again as agthe the others these openings s are covered by a rather by a series oc of tubes of boiler boilerplate plate separated from A each other at fit the enda bends and strengthened by angle iron an article like this is ria rid not the place for an account of the reasons which make inake the tubular form of materials stronger than any other arrangement of them but we may remark that it if the four plates which form the four sides of the tube were laid one upon another the thickness of the whole would not exceed about two and a half inches and would not support a fiftieth part of athe load which may be safely carried over the tubes it needs no engineering nor mechanical ch cb anical knowledge to be able to understand that hardly any accumulated thickness of or such a material laid in a flit shape over an opening I 1 between feet and feet wide would support the hundreds of tons weight made up by the fhe component parts of a railway train resting OB on the middle of it the plates throughout the tubes are double bolted to angle iron iron beams and girders aej and always overlapping each other at the eads ends for further security each joint has placed over it on each side of the plates an extra sheet bolted on both sides of the joint and called a covering plate the object of all these precautions isto is to make the tubes resemble as much as possible similar tubes made of one piece of metal metai many very di delicate licate considerations have to bs be attended to by the engineer ineer who adopts this tubular mode of construction in order to give his roadway the greatest strength with the least weight and cost the condition upon which the attainment of this end depends is is that the relative strain upon each inch of the should be known and phe the strength of the metal at that place proportioned to the stress it is is impossible here to give any idea ozithe data upon which these calculations are made the result however is is that the hardest duty must most be done by the metal sittia situated ted at the ends enis of the tubes and accordingly L this part is is strengthened by a considerable addition to the ordinary number of transverse supports OF 0 angle iron iron As to the plates plater themselves the same kind of calculations have determined that ahat those in in the bottom arid and top ot of the tube should be thinnest at the end and ald thickest in in the middle of the length while this order is rev reversed eased at the si sides desand and the greatest thickness ness of plate is is used ai at the ends the sentences immediately foregoing will prepare the reader for the inform information information atio atlo ry th that tit every sheet of iron iron and every angle iron upright or girder has its place tit in the edifice marked with the greatest accuracy before it is shipped at liverpool and that upon arriving on the bank of the st lawrence it mut ant must not vary half an inch from rom the position for which it was destined but perhaps it will excite wonder at the immense forethought labor and attention to details which are necessary for such perfect and anil long iong before beforehand hand adjustment when vie we state that it is is necessary to determine the dosi nosi position fion tion of 2500 different pieces of aronin iron in each oe 61 the smaller tubes or of 61 pieces in in the whole bridge this is is like numbering the bricks briche 0 of a ahouse house and never putting putt ilig one in be the wrong place the ints i used in in each tube amount in in number to 80 or to more than 2 in in the entire structure arid and reckoning the heads as separate pieces of iron we shall have more than 7 of distinct pieces of metal put together to form the tubular tub diar roadway the exp eap expansion inseon and contraction of metai metal is another circumstance requiring the attention of the architect in in iron every one is 3 of course aware of this phenomenon bu but itlay itman be a novel reflection to many that the vast structure poised so high lush ift in the air above the st lawrence lwrence and apparently app pep so firmly fixed is yet et go going 1119 through aorist anil not in inconsiderable on sid erable I 1 chans chani ns ibs of dimensions and abid even of forms and that instead of its parts being rigidly fastened to their places the metallic roadway is in fact disen disengage gaga I 1 from the stone piers in order ardt to allow the iube tube to td stretch itself on its bed as our readers are doubtless accustomed to do on theirs the principal of expansion and nd contraction in these tubes are two the first is chiefly in in the length which varies in in a flum plum summer mer rummer day some inch and a half balf form forA each tube covering a single opening nand land ani and beten between summer and winter varies about three and a half inches the other is a change in in form arising from rom the fact that the upper floor of the tube is 13 exposed to the thesues suns sunya rays while the lower one is 13 in in the shade tha the consequence is is a greater lengthening of the of the under plates and a certain flex ture of the tube such chanis chandes changes if ir operating on a adass mass mabs of iron iron about two miles long would would be of course very difficult to manage 11 the mode node of pro against its incorv therefore is 9 to divide the whole le length rieth of the roadway into thirteen tubes one over the large central centra larch arch feet long and six oneace on each eile side of it each formed of tayo two tube tubes and each covering covering two of the smaller openings 0 or spans of feet the two tubes thus made into one therefore rest upon three piers across one and resting by the two ends on two others the united tube is firmly bolted down to the pier which supports it in the middle but bit bi hit t the ends rest upon rollers BO so that when they are prolonged by expansion the movement takes place without any resistance the ends of the tubes at the piers where they rest on rollers are of course not in contact there is 13 a space of about a foot between them for any play arising from the cause already described the weight of iron in in the tube over each of the smaller openings is tons an i i over the larger one goo tons thus the weight of iron iron in the bridge will be about tons the progress made in laying the tubes this year has ben been considerable pour four spans are already covered two on each side and from this time to the end of the working season it is expected that two more will be ba completed each fortnight making twelve before the setting in of the winter the setting in in of the severe beadon scabon of our canadian eat ear year will wll of course retard such a work but will not entirely stop iff lff and tube laying will be continued in in spite of frost and wind arld cind rain rain and snow before leaving the tubes we saw a steam rivet avet ing maebane machine which though il it cannot accomplish all the that line jine ine lne owin owing 0 to the difficulty ia in moving moving b it fastens a great many plates beffre they are boup in n their places it con siss of a large steam cylinder having a piston on tl tt e ea projecting bonds of which are a number oadies of dies dibs in the of rivet heads the plates ni mith with ith the J rivet placed in the proper boies holes bein being the then presented to those dies the steam is is allowed allow ed to enter the ca cylinder linder and at once forces the dieb dies against the rivets till they are pushed through the holes and clinched clinch cd descending from the upper works of the brid brad bridge e wf we next took boat for tor the piers of these there are seven completed on each side two are rapidly approaching completion and W two 0 are just on the point of 0 being beg begue t ii it is is expected that unless some lunfors e en event takes place all the piers but one will be finished during the present year or at least advar addan ced so far as to permit of the work proceed eang rg during the whiter winter at lit piers kos nos 10 and 17 we witnessed all the process processes ss employed from the commencement of the day to the laying of the masonry of course the first thing to be done don is to make a dam round the place intended for tor the foundation of the pier interior of which the water is 13 to be pumped ou out so that the mason masons may proceed with the foundations dat ions toe in thing king arid and maintenance of the dam is therefore the chief difficult difficulty of the engineer the piles are driven into the ordinary bottom of the ther river nier but the foundation of the stone is several feet below and the consequence is that the excavation required often destroys the foundation of the dm dern and arid breaches constantly occur all the more inor e easily forthe great depth and rapidity of the current in order to lessen as much as possible the risks of oi these line of bottom on which the dam is placed is rendered as even as possible by wark working a gravel this machine however constantly coms in con contafi tagi with boulders and stones of various various dimensions anti antl ani these thes havi have to be raised for bis this his purpose a diver is is always employed who desce desee descends ads upon the rock to be lifted and holds the ram by which a hole bole for the leuis lewis is made this effected the impediment js raised by a crane these stones are of very defler different nt geological formations arid and bave lave evidently trave traveled jed froma fromm their present site on the icy ley embarkations by which bich A the they were first lift ed from their longinal what was their original resting place we e saw one of twenty tons weight which hd hwd been brought up tip from as many feet below the surface of th ohp river occasionally the break in tue the dam exhibits strange ft eaks I 1 I 1 the ater wa iter will sometimes rise tip lip like a fountain inthe centre of the spice space marked out for the foundation rind and it will lire many hours of research to find the weak spot whence ubence it has had entered the enemy however has to retraced be traced ani and once found the ingenuity and ant patience of the engineer soon conquer speed is a matter mattar of considerable importance in the asi con construction truc tion of works subject to so many accidents as piers b lii nit uit lit t wih wi 11 dam dams s hence 11 e nce the workmen are employed in gangs pangs night and day the light being afforded aldor alfor ded by a lamp with ith an im mense reflector the tile stories stones forthe for the piers have been supplied from the the quarries belonging belor belof ging to the grand trunk company at point clahe clane and from another quarry on the richelieu the stone from the latter is brought down by the st S lawrence and arid champlain railway we havo haic to thank mr lvir hodges the chief superintendent of the works for the contractors and hib hia able lieutenant mr MT arkman tor the kindness with which they afford us all the explanations necessary to enable us gounde to understand the works which we ire saw going on they are entitled to congratulations on the tile bue sue ess with w ith which they have begun and prosecute their arduous fabors tabora in a climate and on oil a river presenting preSeT tinZ so many difficulties they the y expect to finish the entire work with the end ef rf the year 1859 and they will then have erected perhaps the most remarkable specimen of bridge architecture which the world has yet et seen |