On The Testing And Strength Of Railway Materials, &C.

Ill creosotiug timber for Railway Avork , the standard quantity specified by the Great Western ancl Great Northern Railways , is 35 gallons to one load of 50 cubic feet , being 0 . 7 , or gallons , or 71 bs . to a cubic foot ; the oil to be 1 , 000 specific gravity . When railway sleepers and telegraph poles are properly creosotecf , they undoubtedly receive a prolonged life . Sleepers should be specified to be of good , sound , Avell-groAvn Baltic redwood timber , free from sap , shakes , large or unsound knots , aud other defects ,

and to be creosoted Avith at least 35 gallons of creosote per load , to the satisfaction of the company ' s engineer . The preservative properties of creosote appear to be threefold : First , it prevents the absorption of moisture iu any form or under any change of temperature ; secondly , it is noxious to animal ancl vegetable life , thereby repelling the attacks of insects and preventing the propagation of fungi ; thirdly , it arrests the vegetation or living principle of the tree after its separation from the rootwhich is one

, of the primary causes of dry rot and other species of decay . Wherever creosoted timber can be applied it Avould seem advisable to do so , because it not only resists the changes of Aveather , but also adds to the strength of the Avood . On the authority of Messrs . Armstrong and Forster , of Sunderland , we know that a series of experiments proved this to be the case .

The size of the pieces tested was 2 ft . Gin . by 2 in ., by l ^ iu ., and the pressure Avas applied midway betAveen supports 2 ft . apart . Not Creosoted broke Creosoted broke Gain through Avith . with . being Creosqted . Memel fir llcAvt llf f , Scotch fir 13-kwt 15 j- H In each of the above cases the breaking Avei ghts are the average of six tests .

TELEGRAPH POLES . iVcw-creosoted telegraph poles are very short-lived , 7 years being the maximum ; some have decayed in 3 . A fair average Avould be about 5 years . Creosoted poles , on the contrary , are very durable , and as yet sufficient time has not elapsed since the process was applied generally to telegraph poles to say positively ho , v long they will last—certainly twice as long as wcm-creosoted . Much depends upon

circumstances , quality of timber , description of soil in Avhich they are erected , and the way they are creosoted . Under very favourable circumstances 20 years life might be expected ; but an average life of 14 years may safely be taken . The folloAving , from the Architect , well deserve noting : —

"In most of the specifications for Avorks in London , as Builders knoAV , the usual description given for timber is ' Best Memel , Riga , or Dantzic . ' This clause is for the most part liberally interpreted to -mean timber fit for the Avork that has to be done , and it is not the custom to require any positive evidence that the timber supplied to any building is best timber in the timber merchants' application of the Avord ; in point of fact , not 10 per cent , of the timber used in ordinary building contracts is of that particular qualityancl there are no good reasons Avhy it should be .

, " Best Timber , in a timber merchant ' s specification , means timber exceptionally straight-grained ancl free from knots ; and of timber so selected a large percentage'is subject to heart shakes and cuts up unsound , and from the very straightuess aud softness of its quality is not so Avell adapted to sustain 'heavy AA'eights as the second quality , Avhich is not so clear of knots , but as a general rule is sounder and stronger . . 1 n p- > iut of fact , Avhat are called the second qualities of Memel and Dantzic timber do most of the

London Avork of high class , and come into the market as ' Second Memel , ' and ' Good-Middling Dantzic' In some cases , Avhere the timber is used as whole timber , as for piles or heavy Avarehouse girders , the ' Thirds' in Memel or the ' Common iu Dautrie may be used ; but , except for these and similar purposes , they are too coarse for good Avork . And here let me say that the great secret of buying timber to advantage is personal inspection , as different parcels submitted under the same description add specification Avill vary so much in quality as to make a difference in the HCIUHI -V > , n , the builder of 20 to 25 per cent .