38 



I have asked our kind friend, the Bishop of Barbadoes, to en- 

 deavour to collect some and send them over alive, ^Yhen, should 

 they come safely to hand, I hope on some future occasion to sub- 

 mit them'to the Society. 



Captain M'Dakin, in speaking of some phenomena connected 

 •with freezing, deseribed a peculiar action witnessed by him a few 

 years ago on the Dane John wall, and referred to the subject of 

 their last meeting, connected with glacial action arising from 

 the accumulated snows of many centuries of winters to which 

 the gravel drifts, boulders, and glaciated rocks bear witness the 

 effect ]of the property that ice possesses of comporting itself 

 under pressure in a somewhat similar manner to a plastic mate- 

 rial. Nor is this entirely confined to ice, for the metals Avhen 

 brought under the coining press are made to assume the forms 

 of the dies, the solid particles sliding over each other. In a 

 similar manner are formed metal articles in domestic use, such 

 as meat covers spoons, and bowls. In the bidlet-making ma- 

 chines at the Royal Arsenal the lead is forced from a press 

 through an aperture in a steel plate, about half au-inch in size, 

 from whence it issues in a long bar many yards in length, which 

 is caught and coiled round a drum. From this coil the bidlets 

 are pressed cold. So, also, is made the leaden piping, technically 

 called " compo piping" used for gas, also the leaden pipe lined 

 with tin for conveying water. The metal in a solid form being 

 driven out through a steel die in which is placed a mandril of 

 the size of the bore required. In conformity to the same action 

 of matter ice may, hj considerable pressure, be made to issue 

 from a'small orifice in a long bar. AVater, in cooling down from, 

 say, sixty to thirty-two, contracts in volume till it reaches a little 

 below fortj' degrees, when the reverse takes place, so that on 

 becoming solid it occupies a greater space than the original liqiiid, 

 and with a force sufficient to rend rocks, stones, iron pipes, and 

 even gun bai-rels, but in a very thick and strong steel cylinder, 

 water may be exposed to a temperature below freezing without 

 becoming solid. The experiment was performed in this manner. 

 A strong steel cylinder, with a tightly fitting sfrew plug, and 

 containing a loose piece of metal was prepared ; this being filled 

 with water, was placed in a freezing mixture, but the steel being 

 sufficientlj' strong to resist the expansion of the water it never 

 became solid, as was made evident by the sound of the loose 

 piece of metal striking the ends of the cylinder as it was turned 

 over. The expansion, however, is far more than any ordinary 

 vessel can withstand, and must be very great, being sufficient in 

 a strou"- vessel with a narrow opening, to cause a thread or bar 

 of ice to flow out, producing in this manner the curious effect 

 witnessed on the Dane John waU, where the porous bricks form- 

 ino- the coping, were, one frosty morning after rain, seen to be 

 brTstlin* with spines of ice, in some cases beautifully striated and 



