14 Prof. J. Joly on Scientific 



about I second after the first of the group of six bell- 

 strokes. The distance is determined by counting up these 

 radio dots until the first stroke of the six submarine signals is 

 received. The number of dots thus determined gives the 

 distance in half sea-miles. It will here be seen that two 

 unsymmetrical groups of bell-strokes are emitted. This 

 appears to have in view the certain identification of the 

 station and of rendering it easier to first pick up the signals. 

 The number of the lightship is stated to be spelled out by 

 the signals. Numerical examples are added showing- 

 readings of distance to the quarter mile. In this installa- 

 tion the size of the radio antenna is designed to send out 

 signals which will not be heard much beyond the range of 

 the submarine bell, in order to avoid unnecessary inter- 

 ference with near-by radio stations. 



We may now picture to ourselves the practical application 

 of this system of synchronized submarine bell-strokes and 

 radio dots installed at Fire Island. We are on board a liner 

 going westward and — we will suppose — are deep in a fog 

 bank. Our whistle emits prolonged and far sounding blasts 

 every two minutes. In former years, when the present 

 writer experienced just such conditions approaching New 

 York, frequent determination of depth was the only means 

 available for fixing with any approach to accuracy the 

 position of the ship, and hours were thus wasted, gradually 

 stealing closer to the land. Let us now, however, imagine 

 the little instruments on Fire Island busy tapping out to the 

 mariner the knowledge he so anxiously desires to obtain. 

 The speed of the ship is but little reduced, for ample warning 

 by wireless dots and submarine bell stroke may be counted 

 on. And now upon our ship the wireless operator reports 

 to the bridge the first wireless dots. Then the bell-strokes 

 are picked up. There are the six — pause — eight strokes 

 once every 40 seconds. There can be no doubt as to what 

 he is listening to. He waits for the first of the group of 

 radio dots and counts them up till he hears a bell-stroke. 

 He finds that the bell-stroke falls — say — just between the 

 12th and 13th radio dot; that is to say he must divide 12J 

 by 2 for the distance in knots. He reports, accordingly, 

 6J miles from Fire Island Lightship, the signals being heard 

 on the port bow. The land fall is made. 



That radio signals and submarine bell could be worked 

 reliably from a buoy, and, if desired, in combination with 

 light flashes, seems very probable. The emission of the 

 instantaneously propagated signals would be started by the 

 bell-stroke. The wireless would have a range comparable 



