SCIENCE SIFTINGS

New Zealand Tablet, 17 March 1921, Page 46

SCIENCE SIFTINGS

(By “Volt.”)

Pencil Points. JHj A “lead” pencil is not made of lead at all, but graphite with several other ingredients. Pure graphitUl alone was once used, but it ‘was found to be too expensive, and so a soft gutless clay was added. . When the ingredients are mixed in the required fashion, they are squeezed through a strainer, and the long, thin rods are produced. When these are dry they are placed on a grooved board and then smeared with glue. Another grooved board is clapped on top of it ahd the two are pressed together. They are then planed off until the pencils are rounded out. In Praise of Walking. The ideal form of exercise is walking. One of its greatest advantages is its almost universal availability. Then, too, unlike many gymnasium forms, it does not develop one set of muscles and neglect others. It calls • into greater or lesser degree of action most of the organs of body and mind, and is less liable to result in serious exhaustion than any other exercise. Professional walkers are long-lived, and are good insurance risks, but piofessional athletes are shunned by life insurance companies because too many of them die early of enlarged, hearts or hardened arteries. When a man walks for exercise, he generally does so out of doors, and his whole physique participates in the effort. The blood absorbs the resulting carbon dioxide, and races to the lungs to discharge it and receive increased quantities of oxygen. The heart responds with stronger impulses, and sends new nutriment to the remotest tissues to repair their loss. The heat centres respond to the stimulus, the cutaneous capillaries expand, and the sweat glands eliminate more freely the retained impurities. The attention of eye and ear is required to direct his progress ; and interest in his environment is awakened, so that he forgets that exercise is his object, and enjoys what Stevenson calls “the wonderful pageant of consciousness.” Making Violins Talk. Experiments made by two young Danish engineers promise to revolutionise wireless telegraphy and telephone (says London Tit-Bits). They have discovered a new force, resembling electro-magnetism, by means of which it will be possible to ease the capacity of a wireless station to receive or dispatch messages. ' The two inventors picked up wireless messages from different European stations, and by a specially const! ucted apparatus were able to take them down at the rate of six hundred words a minute. Mechanical recording of wireless messages has been attempted already in Erance and Germany, but the highest rate has been one hundred and twenty words a minute. The force by which this is" made possible is developed by sending an electric current through certain substancesfor instance, lithographic stone (a slaty limestone). During an experiment one of the inventors went to a house connected with the demonstration-room by wire and played on a violin. , This was distinctly heard by the gathering in the demonstration-room. In fact the sound was magnified so much that listening became almost unbearable.' The inventor then talked into his violin, and another violin in the demonstrationroom repeated his words.