Cleanings.

Kaikoura Star, Volume XIV, Issue 759, 27 July 1894, Page 7

Cleanings.

The Periodicity of Earthquakes.

From statistics collected by Mr C. Davison (London Royal Society), it appears that earthquakes do not occur irregularly, but increase and decrease regularly both in frequency and intensity, bavins’ two principal periods, an annual and semi -annual. The maximum of the annual period takes place in the northern hemisphere in November, December, or January ; in the southern in the months from April to August, thus always occurring in Winter. Mr Davison thinks that this periodicity is connected with the annual variation in barometric pressure, though this is difficult to prove. The probable cause of most nonvolcanic earthquakes is the slipping of two subterranean rock surfaces one upon another with friction. Such slipping might be hastened by a slight cause, such as a change of barometric pressure. Whatever the cause of the periodicity may be, it appears to be only auxiliary or determining, merely letting off the energy without causing it, as the pulling of the trigger of a gun sets loose the energy of an explosive within it.

Curious Effects of Extreme Cold.

Amongst the many interesting facts announced by Dr Dewer in his last lecture were the effects of extreme cold on the cohesional power of metals. The tensile strength of iron at—lBoC. is just what it is at 15C. It will take a strain of 60 instead of 30 tons to the square inch, and equally curious results have come out as. to the elongation of metals under these conditions. A fully saturated magnet is found to have its power greatly increased by reduction to —1800. The intense cold has a strange effect on colour. Professor Dewar sponged a scarlet card (painted with mercury iodide) with liquid air aiid pointed out that the brilliant scarlet changed to orange, but recovered its original tint immediately it got warm again. Many brilliant experiments were made by sending electric discharges through exhausted glass globes. But all of the wellknown phenomena of phosphorescence ceased so soon as intense cold was applied—the electricity tried to pass by any route rather than through the globe. ‘ What did this mean ?’ said the professor. ‘ Obviously that something was now frozen out which had before enabled the electricity to pass across the vacuous space.’

A Curious Fact.

By a singular provision of nature—very obnoxious no doubt, to Sir Wilfrid Lawson, but dear to the souls of unregenerate humanity whatever produces sugar for one's toddy produces also on the same stem the toddy to put it in. Thus the self-same cane supplied Mr Stiggins with his famous pine-apple rum and with the four large lumps which he employed to sweeten it. Thus, too, John Barleycorn, when ‘ for England’s good he yields his blood ’ in the form of bitter beer, passes first through the sweet stage of malt, in which condition he can easily be converted into the substance known as maltose or malt-sugar. It is the same with palm-juice. When simply boiled down it produces palm sugar, but when allowed to ferment it turns into an excellent substitute for Bass’s pale ale, called palm-wine or toddy. This is, indeed, the original and only genuine toddy, all others being spurious imitations.— Cornhill.

The horse shoeing smith first appeared in Germany, where iron shoes were first used for horses.

Chimneys were first put on houses of more than one story in Italy in 1347.