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

to ascertain their tensile strength , Avhich must not be less than 800 lbs . on the area of 2 \ square inches . 3 rd . The sloAv-setting cement , when gauged neat in the mould , must not become firm in less than throe hours ; the quick-setting must assume a firm condition within half-an-hour . The test of firmness will be that of resistance to the finger-nail .

These tests are applied after each delivery . As Mr . Reid attaches great importance to what is called '' heavily-biunt'' cement ancl reiterates his vieAvs on this point repeatedly , Ave may just remind the reader that some eminent practical authorities are not so decisive in regard to the advantage of vitrification . Mr . Grant , O . E ., in the course of his papers on the " Strength of Cement " ( read before the Institution of Civil Engineers ) , points out that the sloAv-setting of

this heavily-burnt mixture renders it unsuitable for some positions ( as in moving water ) Avhere a lighter cement Avould set more quickly . He added that" another inconvenience to AA'hich this heavily-burnt cement exposes the engineer Avas the almost certainty that it Avould not bo properly ground . Theoretically the cement should be an impalpable powder , ancl every grain of sand a matrix round Avhich the cement should form a film or coating , but this could scarcely be the case AA'ith a material Avhich it Avas so difficult

to reduce to poveder as the heavy cement in question . On the contrary , if carefully scrutinised by passing it through a sieve , or by Avashing it , a considerable residue of particles resembling sand Avould be found comparativel y inert in their character , AA'ith very feeble setting properties , and of a nature to diminish the amount of real sand which the cement would otherwise carry . He might also add that the coarsest ground cement being found to Aveigh the heaviest , tho exaction of a very heavy specific weight , unaccompanied by any other restriction , offered an inducement to imperfect pulverisation . ( To be Continued . )

Notes On Literature, Science, And Art.

NOTES ON LITERATURE , SCIENCE , AND ART .

BY BRO . GEOEGE MABKHAM TWEDDELL . Author of " Shakspere , his Times and Contemporaries , " " The Bards and Authors of Cleveland and South Durham , " " The People ' s History of Cleveland and its Vicinage " "The Visitoi- ' s Handbook to Reclear , Coatham , and Saltbwn by the Sea , " "The History of the Stockton and Darlington Railway , " § c , fyc .

GHSTAVE DORE is said to have produced not less than fifty thousand drawings , to illustrate various literary works . Amongst the numerous useful public servants Avhich Great Britain is fortunate enough to possess , I greatly question Avhether any can excel those of the Civil Service for industry , intelligence , and integrity . Yet I see certain of our neAvspaper Avriters are setting up their Avar-Avhoop because some of them indul ge in literary occupations durin "

their leisure ; a pursuit I should have thought AA'hich AA'as rather to have been commended than censured . If it can bo SIIOAA ' H that any of the Civil Service neglect their dutieseven though it be for literary or scientific pursuits—there is a proper Avay of coming at them , as at other men . But really to blame them for Avhat every Britisher ought to be rather proud of , is to " bang Banaghen , " Avhoever that proverbial personage might be , ancl heAve are told " banged " a gentleman to mention whose name not be quite

, may parliamentary . I remember a friend of mine Avho , being then engaged to inspect hon for the purchaser , and haA'ing much leisure at intervals , occupied his spare time by correcting proofs of the literary articles AA'hich he had Avritten Avhen in his lodgings of an evening , whereupon he was reported to his employer , Avith a similar degree of justice to