34 



is it less remarkable that whilst the giants of the earth, the 

 huge reptiles of the Mesozoic ages and the no less gigantic 

 mammals of the Cainozoic, have left but their tusks and bones 

 as memorials that they ever lived, and man who has reared the 

 pyramids, constructed railways, dug canals, and built cities, has 

 but dotted and scratched the surface of the earth, these minute 

 creatures have paved the ocean's floor, constructed continents, 

 and upheaval having raised their work above the waters, 

 it stands in many places a thousand feet above the sea. The 

 chemical natiu-e and analysis of chalk having been shown with 

 the aicl of diagrams, some of the pure chalk from Shoreham 

 Downs containing ninety-eight per cent, of carbonate of lime, 

 the industrial uses to which it has been put were entered into, 

 the manufacture of cements and some of the properties of com- 

 mon mortar. In connection with the latter it is recorded, as an 

 interesting fact, that mortar analysed by Dr. Malcomson from 

 the interior of the Pyramids, and now perhaps three thousand 

 years old, still contain caustic lime. Captain McDakin stated 

 that from some of his own experiments he found the upper chalk 

 when dry capable of absorbing twenty three per cent, of water, 

 the lower chalk from Folkestone twenty-one per cent., and the 

 Chalk Marl eleven per cent. ; whilst some of the hard grey chalk 

 from the Abbot's Cliff only absorbed eight per cent., showing 

 how, after heavy and continuous rain, falls of chalk from the 

 sea cliffs and railway cuttings are most likely to happen, some- 

 times bringing about such destructive results as those which 

 took place between Dover and Folkestone not quite two years 

 ago. The architect and builder have also made use of this rock 

 as a building material, examples of which occur in Louth Abbey, 

 Lincolnshire, and St. Pancras priory at Lewes in Sussex ; the 

 latter being eight hundred years old, speaks well for its dura- 

 bility. The underground works of Dover Castle also afford an 

 instance of the manner in which it may be excavated on an 

 extensive scale without the use of masonry to hold it up, these 

 galleries in some jjlaces being in three tiers. 



In concluding, Captain McDakin remarked how so simple, so 

 common a thing as a piece of chalk, when looked into, opened 

 out to the thoughtfiil inquirer a whole volume of instruction, 

 presenting to the mind the great laws of nature, chemical 

 affinity and vitality acting together to produce results of which 

 thej', being non-intelligent, can have no knowledge, created be- 

 ings working together at their aj^pointed tasks to bring about that 

 which is so far above their immediate recjuircments, so far above 

 the conditions of their existence that the most unobservant can- 

 not fail to perceive the directing hand of Deity. 



