320 



Popular Science Monthly 



Holding the Morse Key 



Having mounted the key, the next thing 

 to learn is how to hold it properly. There 

 are variations in the "grip" from operator 

 to operator, but the essentials are that the 

 fingers should be arched into an approx- 

 imate quarter circle and have their tips 

 resting on top of the knob, the thumb 

 should press gently but firmly on the side- 

 rim of the knob, the wrist should be held 

 up clear of the table surface and the elbow 

 should rest upon it. The key should be 

 pressed shut, never "tapped," and should 

 open easily through the action of its own 

 spring. The muscular impulse which closes 

 the circuit must be gentle and firm, coming 

 from the full arm. The wrist must not 

 be stiff, nor yet must the lower arm muscles 

 be used (through the wrist-joint) for the 

 entire key manipulation. The proper dis- 

 tribution of muscular effort, and the cor- 

 rect use of the inertia of the fore-arm 

 for rapid sending can only come from long 

 practice; nevertheless, it is important to 

 bear the above suggestions in mind at 

 first, so as to form correct habits at the 

 beginning of work. 



Practicing Dots and Dashes 



The first actual sending should consist 

 of dots only. Make dots slowly, being 

 careful to keep the interval between each 

 pair of them exactly the same length as 

 the dots themselves. As you find that you 

 can make them perfectly, increase the 

 number until you can send three or five 

 per second without difficulty. Then take 

 up dashes, slowly at first, increasing the 

 speed till about one per second can be 

 made perfectly. Remember that when 

 sending dashes the space between each 

 pair of signals must be only one third as 

 long as the dash itself; this is the only 

 difference between the rapid series of dashes 

 and the slow series of dots. Next take up 

 alternate dots and dashes, being careful 

 to keep the spaces between the signals 

 correct. Although speeds corresponding 

 to those suggested must be attained 

 through practice, never sacrifice accuracy 

 for the sake of sending fast. Reliable, 

 smooth and carefully-spaced transmission 

 is the first requisite; speed follows as a 

 matter of course. 



When the student overcomes the difficulty 

 of changing from dots to dashes by prelimi- 

 nary practice of the sort just described, he 

 may begin sending Morse letters and words. 



The first two groups of letters (Fig. 2) 

 and the practice words given here will 

 afford ample work for some time. As 

 soon as the first six letters are thoroughly 

 learned, the third group may be used. 

 New practice words and sentences may 

 now be made up easily, since the fourteen 

 letters using three or fewer signals permit 

 spelling a large number of words. At this 

 stage of practice it is advisable to commence 

 reading by sound. Consequently an auto- 

 matic sender or a companion student is 

 needed. In the next article, circuits for a 

 buzzer telegraph line, over which messages 

 may be sent between two houses or rooms, 

 will be described. Meanwhile learn and 

 practice the code, and remember that care 

 and accuracy are the two essentials for 

 which to strive. 



(To be continued) 



A Fixed Adjustment Detector 

 Easily Made at Home 



A SIMPLE "permanent" detector is 

 constructed of materials found in al- 

 most every experimenter's workshop. 



Secure a piece of mica j4 in - square. 

 Next, select a piece of sensitive galena. It 

 should not be larger than a B-B shot. Cut 

 a hole, just the shape of the galena, only 

 slightly smaller, in 

 the center of the 

 square of mica. 

 Push the galena 

 half way through 

 the hole and fill up 

 the cracks between 

 the galena and 

 mica, with glue. 

 Be careful, how- 

 ever, not to get any glue on either protrud- 

 ing face of the crystal. 



While waiting for the glue to harden, 

 remove the two thumb-nuts from the bind- 

 ing posts on any ordinary dry battery. 

 Glue these nuts, top outwards, to each side 

 of the mica so that the galena will be 

 between the burrs but touching neither of 

 them. After the glue is dry the projecting 

 mica may be cut away. 



Pour fine brass-filings in on either side of 

 the galena and screw in on either side a 

 brass bolt taken from a dry battery. 



The whole is then mounted on a suitable 

 base and held in place by spring clips. 

 This detector may be easily adjusted by 

 simply tightening or loosening the bolts as 

 desired. — Edward M. Weyer, Jr. 



Filings in nuts be- 

 tween the bolt ends 



