SCIENCE NOTES.

Digger (Invercargill RSA), Issue 7, 30 April 1920, Page 3

SCIENCE NOTES.

r STING ROCK WITH WATER. rA writer in a German technical paper, tfescribes a hydraulie device for blowing Uy rocks. It is based on the principle of ifp hydraulie press; enormous pressurea ©ro set up witliin the rock, which eventnally bursts. The prassure is transmitted by a pipe-line to a cylinder 85 millimetcrg hl diamcter in which eight pistons may be ©aecessively displaced telescopically. The cylinder is inserted into a hole, drilled by an electrical drill in the rock to* be Blown up. The pistons bury themselves in the rock one after anotlier and blow fcp the rock. J ROCKET TO REACH THE MOON. i:v According to an announcement auth©rised by the Smithsonian Instituto at Washington, a high efficiency roc-ket has been invented by Professor Robert Godidard, oi* Clarke College, capable of shooting upward 200 miles or more, and it is suggested that after a few practical experiments a rocket can be constructed which will reach the surface of the moon. Tbe principle of Professor Goddard's rocket is a series of recliarges, which explode one after another as the missile proceeds, and the hope is expressed that a rocket will shortly be fired containing recotding instruments, which, when recovered, will give information regarding the natore of the higher levels of the earth s atmosphere, its chemical compositiouj temperature, electrical nature, density, ozone content, etc. FIRE FIGHTING WITH DYNAMITE. the conquest of one of the largest fires in gas well history in California, has clemonstrated that dynamite is far more effective than water in fighting the most stnbborn fires. A hundred and ninety miliiou cubic feet of gas was being consumed every 24 hours — enough to supply a city. Water, mud and earth wero poured into the crater of the well, to no avail, Then, by means of cables suspended from nearby derricks, 150 pounds ||©f blasting gelatin was swung directly into the flainc, 30 feet from the mouth of the well. The gelatin and the electrie - .wires attached to it were insulated against the terrific heat and the explosive 1 discharged by an electrical spark as it i reached the flame. The explosion snuffed : om the tower of fire, and immediately f streams of water were played upon the Well to prevent the fire starting again. WEIGHING THE EARTH. A standard experiment which deserves \ to be carried out more frequently than seems customary is that of weighing the i earth. The fact is, the earth weighs something like 6,000,000,000,000,000,000, tons The law of gravitation tells us that all bodies attract each other with a force that depends, among other things, upon the relative masses of the bodies involved. So in the experiment, two small spheres, carefully weighed to the most excruciating accuracy, are attached at the end of a small rod. The spheres were freely suspended so that they could be swayed in any direction. They were hung by threads of quartz drawn out to oneI twelf th the thickness of an average human hair. Next on the list of properties were two lead balls of about ten pounds each. placed in the vicinity of the swinging spheres, these lead balls at once made thf.r presence felt by an infinitesimal 'deviation of the spheres, which was magnified by being refiected in a large mii-ror forty feet away. On the basis of the known weight of the tiny spheres and the lead balls, the movement which the presence of the latter caused in the former ■ made it possible to calculate the force which the lead had exerted upon the spheres. At the same timo, it was already known what force the earth, with its gravitational field, was exerting on the leaq balls. So the weight of the earth was then found as the fourth member in a proportion of elementary simplicity.