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Star (Christchurch), Issue 19270, 6 January 1931, Page 13

Glass may be cut under water with ease, to almost any shape, with a pair of shears or sttong scissors. Two things are necessary for success. First, the glass must be kept level in the water while the scissors are applied; and, secondly, to avoid risk, it is better to perform the cutting by taking off small pieces at the corners and along the edges, and so reduce the shape gradually to that required. The softer glasses cut the best, and the scissors need not be very sharp. The heat which accompanies the overcoming of friction is an example of the principle of the conservation of energy. The power expended in overcoming the friction between two bodies —in overcoming the resistance offered bv the pressure of one against the other—produces an amount of heat ekactly proportional to that power. The heat produced is nothing but the original power in another form, and is itself capable of performing mechanical or other work.