108 Things not generally Known. 



land should be laid prostrate, to form the bed over which it 

 would continue to roll an uninterrupted sea. 



THE CHALK FORMATION. 



Mr. Horner, F.R.S.. among other things in his researches 

 in the Delta, considers it extremely probable that every par- 

 ticle of Chalk in the world has at some period been circulating 

 in the system of a living animal. 



WEAR OF BUILDING- STONES. 



Professor Henry, in an account of testing the marbles used 

 in building the Capitol at Washington, states that evrey flash 

 of lightning produces an appreciable amount of nitric acid, 

 which, diffused in rain-water, acts on the carbonate of lime ; 

 and from specimens subjected to actual freezing, it was found 

 that in ten thousand years one inch would be worn from the 

 blocks by the action of frost. 



In 1839, a report of the examination of Sandstones, Limestones, 

 and Oolites of Britain was made to the Government, with a view 

 to the selection of the best material for building the new Houses of 

 Parliament. For this purpose, 103 quarries were described, 96 build- 

 ings in England referred to, many chemical analyses of the stones were 

 given, and a great number of experiments related, showing, among 

 other points, the cohesive power of each stone, and the amount of dis- 

 integration apparent, when subjected to Brard's process. The magne- 

 sian limestone, or dolomite of Bolsover Moor, was recommended, and 

 finally adopted far the Bouses ; but the selection does not appear to 

 have been so successful as might have been expected from the skill and 

 labour of the investigation. It may be interesting to add, that the 

 publication of the above Report (for which see Year-Book of Facts, 1840, 

 pp. 78-80) occasioned Mr John Mallcott to remark in the Times journal, 

 " that all stone made use of in the immediate neighbourhood of its own 

 quarries is more likely to endure that atmosphere than if it be removed 

 therefrom, though only thirty or forty miles :" and the lapse of com- 

 paratively few years has proved the soundness of this observation.* 



PHENOMENA OF GLACIERS ILLUSTRATED. 



Professor Tyndall, being desirous of investigating some of 

 the phenomena presented by the large masses of mountain-ice, 

 those frozen rivers called Glaciers, devised the plan of send- 

 ing a destructive agent into the midst of a mass of ice, so as 

 to break down its structure in the interior, in order to see if 

 this method would reveal any thing of its internal constitu- 

 tion. Taking advantage of the bright weather of 1857, he con- 

 centrated a beam of sunlight by a condensing lens, so as to 



It is scarcely too much to say, that from the collection of specimens of 

 building-stones made upon this occasion, and first deposited in a house in Craig's 

 Court, Charing Cross, originated, upon the suggestion of sir Henry Delabeche, 

 the magnificent Museum of Practical Geology in Jermyn Street; one of the most 

 eminently practical institutions of this scientific age. 



