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 itself. If you bring heavy ordnance into the field with ranges of from 6 to 30 miles, and mount the guns so that they fire without any disturbing shock and supply them with powder and projectiles so uniform in character that you can rely on the gun repeating its performance with a deviation of at most a few yards in the point where the projectile strikes the ground, as I have described, it is not only an advantage to have effective observation of all that your guns are doing but it becomes an absolute necessity that you should have it in order to get an adequate return for the cost and labour of bringing the guns into the field. This service was rendered by wireless telegraphy.

To airships or long distance aeroplanes, wireless telegraphy has rendered special service. They are furnished with instruments which can not only receive wireless messages but can be made to indicate the directions from which they come. Now you must remember that the civilized parts of the globe are dotted over with powerful wireless installations which are continually pouring off into the ether 40