The Nome daily nugget., 1918-01-07
MECHANICAL bL00DH0uNDS
 TO RUN DOWN SUBMARINES

Walking at night along q lonely
 road where bandlts are lurking. the
 prudent man takes q good dog. For
 the dog can scent the bandit from afar
 and go for him in the darkness, while
 the man, with only his eyes and ears
 to guide him, is not likely to become aware of the hostile presence until he
 is attacked.
 Applying this reasoning to the prob
 lem of the U boats, H. Gernsback and II. Winfield Secor, conceived the idea of a mechanical counterpart of the bloodhound--an electric seadiving dog" which can be turned loose in the sea to go hunting for submarines. Instead of smelling out it's quarry, however. as does the dog, 1t would be attracted to the submarine by delicate mechanical ears. It Is really torpedo, controlled by sound.
 MT. Gernsback and Mr. Secor are both experts in everything appertain- ing to electricity. They arc the cd itors of the Electrical Experimenter. and in the September number they described their picturesque device.
 Starting and controlling machinery by sound alone is nothing new. There has been on the market for more than a year q toy that Is q good example of the principle. It Is dog In a kennel; when the boy calls to it, d cicrophone on the dogs body catches the sound Of the voice, starts some simple mech a.nism, and the dog walks out of the kennel. It is on precisely this princi- pie that Messrs Gernsback and Secor would make their submarine blood hound.
 They propose that a standard torpedo hc equipped with several super-sensi- tive microphones provided with certain tone-fllters well known to electrical engineers. On coming with range of the sound of U boats motor. the microphones would actuate an audion amplifier or Browns telephone relay, and this in turn would close or open control circuits connected with the pro- pellor, rudder and diving plate mechan- Ism of the torpedo. This would make the electric bloodhound head straight for the U boat until 1t struck 1t. A submarines motors have been de- tected with microphone-a -audiona at distance of more than twenty miles Though they cannot be made nbsolut- ty noiseleSs by mounting them on felt and other sound -deadening sub stances, the Germans have succeeded in minimizing their noise. Sound, however. travels much better and far ther in water than in air.
 If you don't think so," writes Gerns- back and Secor. next time you arc in your bath tub. submerge both cars in the the water and slightly rub two fingers together-under the water, of course. You will be surprised how distinctly you can hear the slightest noises. Therefore. even if the enemy submarine muffles it's motors, we will still be able to hear the U boat ma chinery over q distance of several miles. And that is all we require.
 Tt should also Do borne in mind that this idea does not depend en- trely upon tho principle of micro phones hearing the hum of tho motors alone The Gernans might In time make their motors entirely noiscless- although the authors very much doubt that it can be done. There remains the very loud Round of the propellers the water. This cannot be by my possible means. un- less tho U boat lies perfectly still. And n U boat can't always lic perfectly still: 1t must move sonettme. Then, too. during the night 1t is forced to como to the surface. running it's Deisei oil engines in order to charge the stor- age batteries. And 1t is tnconceivable how the noise of these powerful en- g1nes c1uld be deadened entirely so that tho super sensitive microphone- audions would not detect 1t. when they oncc came within reasonable range.
 Our electro .meo hanical bloodhound then. thanks to an electric brain and electric motors, will start at once in the direction of tho U boat, as aoon as he picks up tho noise. Just like his live brother. he will then guide us to the Invisible enemy as certain as fate.