782 



Popular Science Monthly 



Tubular Quenched Gap 



A PATENT for a novel form of 

 quenched spark-gap is No. 1,132- 

 589, issued in 1915 to F. H. Kroger. 

 In the illustration is shown one of the 

 diagrams forming part of this patent. 

 The gap units are made up in groups of 

 two sparking spaces connected in series, 

 and each unit slips into a pair of clips 

 much as does an ordinary cartridge fuse. 

 This gives complete interchangeability 

 and makes it possible to substitute new 

 gaps for any which happen to break down, 



Interchangeable gap units for a tubular 

 quenched gap 



without disturbing the sections which re- 

 main in useful condition. As may be seen 

 from the illustration, each unit has as 

 its most important parts the central 

 tube 10 and two shorter cylinders 6 and 

 6a, which slip over the inner tube with 

 a small space between them and which 

 have their ends expanded to a consider- 

 ably larger diameter than their central 

 portions. The outer tubes are supported 

 by the grooved insulating disks 7, 

 which serve also to hold them con- 

 centric with the inner cylinder 10. 

 Between the end supports and at the 

 extremes of the units are placed soft 

 rubber washers 8, and the entire struc- 

 ture is clamped between washers and 

 the nuts 9, so as to form a rigid, air- 

 tight assembly. The spark passes 

 between the inner cylindrical surface of 

 the cylinder 6 and the upper, outer and 

 parallel surface of 10, and, after the 

 current traverses tube 10 to its lower 

 portion, it passes from the lower outer 

 surface of 10 to the inner and parallel 

 surface of 6a. The current is then led 

 to the second unit through clip 4c, and 

 jumps two more gaps. As many gaps 

 may be placed in series as needed. The 

 spacing between sparking surfaces re- 

 mains constant regardless of the pressure 

 on the gaskets. 



An Unusual Recording Receiver 



IT has been known for many years that 

 a wireless telegraph power trans- 

 former connected directly to lighting of 

 power lines would often set up, in those 

 supply circuits, very severe disturb- 

 ances. Unless proper protective meas- 

 ures are resorted to, it sometimes 

 happens that the operation of a wireless 

 telegraph transmitter thus connected 

 will cause sparking, insulation break- 

 downs and other troubles at some 

 distance from the sending station. In 

 a plan disclosed in U, S. patent No. 

 1,143,799, issued during 1915 to R. B. 

 Avery, these line disturbances are 

 made use of to record or make evident 

 the operation of a wireless transmitter. 

 Referring to the figure, it is seen that 

 the primary 2 of a step-up transformer 

 I is connected to the alternating current 

 power lines 3. One terminal of the 

 secondary coil 5 is led to the adjustable 

 spark-gap 6 through wire 4, and the 

 circuit passes thence through wire 9 to 



System for recording messages received by 

 power lines 



the swinging plate of a special condenser, 

 10. The other plate of this instrument, 

 8, connects through 7 with the second- 

 ary coil and is separated from 10 by the 

 insulating sheet ii. The pivoted sheet 

 10 is mechanically connected through 

 21 to the contact apparatus 12, which 

 comprises a lever 19, moving and fixed 

 contacts 18 and 15, and an adjusting 

 spring 17, as shown. When this contact 

 is closed, current flows from battery 25 

 through the local lines 22, 23, and the 

 sounder or recorder 24 is operated. 



In using this receiver, the spark-gap 6 

 is opened just beyond the point where 



