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letters, the eye of the instrument being directed to one letter 

 at a time, and the blind can be trained to recognise these 

 sounds and form them into words, which were read by a blind 

 operator at a rate of about 25 a minute. At the National 

 Physical Laboratory tests are now made of the resistance to 

 shock and fatigue of materials, as well the tests for tension 

 and strain, as the strongest materials are not always those that 

 will last best when the strain is long continued. Measurements 

 are also made to a millionth of an inch. The British Scientific 

 Instrument Research Association, formed in 1918, has carried 

 out many important investigations and produced various things 

 and methods which were much wanted, such as improvements 

 in glass polishing, solders for aluminium and cements. 

 Another useful invention is for de-sensitizing photographic 

 plates, so that the extremely sensitive ones can be developed 

 with more light. A very rapid X-ray plate has also been 

 produced and a kinematograph projector with a rotating ring 

 of mirrors, which is said to prevent the flickering caused by 

 the shutter. It is found that a good deal can be learnt about 

 the bottom of the sea from photographs taken from aeroplanes, 

 which shew to a certain extent its features. In view of the 

 great increase in the cost of coal, power derived from other 

 sources is much under consideration, especially perhaps tidal 

 power, and an elaborate scheme for utilizing the high tides of 

 the Severn has been proposed. The variable heights of tides 

 are one difficulty, but the power is there, and it is chiefly a 

 question of the primary expense in developing it. The inland 

 water power of this country is also considerable, though very 

 inferior to that of Norway and elsewhere. The pressure wave 

 in water resulting from an explosion is found to travel at 

 practically the same rate as the sound wave in water, 4,900 feet 

 per second. Oil is being more used in ships instead of coal 

 and the extraction of oil from coal at the pit's mouth has been 

 proposed. By the use of fuel oil on a large ship, the Aquitania, 

 the stokehold staff was reduced from 350 to 84 men, and there 

 are also great economies in loading, three men being required 

 for six hours instead of 50 for 108, as well as in weights and 



