Page:Popular Science Monthly Volume 90.djvu/165

 Popular Science Monthly

��149

��crease the current strength as demon- strated by his many experiments in this field. On exposing one of the

���y\ /OPAQUE BOX

��An impxilsion cell which has a solu- tion of salt, sulphate copper and water

plates to a strong light a current was generated, proportional to the intensity and varying with the distance of the light. The peculiar fact was also noticed that on running the exposed plate along the spectrum, that is, exposing it to all the colors of the rainbow, it was positive at the red end but changed to negative as it neared the violet.

As yet, there has been no plausible explanation as to the mysterious rela- tions between heat, light and electricity, yet the phenomena exhibited by these peculiar cells may be more clearly understood by the application of Dr. See's new theory of light which states, that: "The whole theory of ether is abandoned as having no existence, light being caused by electrically charged particles, shaped like eggs, revolving about their axes, and that electricity itself cannot be separated from matter, but always carries matter along with the currents."

There is a fascination about research work in this comparatively new field of photo-electricity which should entice the experimenter who delights in solving scientific problems; for the solution as to the nature of electricity will probably be found sooner or later by the simple appli- cation and arrangement of the facts gleaned from a patient scientific research into fields, which as someone has said, "makes thinner in places, the boundary between the known and the unknown." — ^A. R. MacPhersox.

��Inexpensive Stranded Aerial Wire Made of Small Copper Wires

COPPER wires may easily be twisted together for antenna conductors by using a hand brace or drill. One end of the strand of wires is fastened to a post or other support, the other end is secured in the chuck of the brace or even merely bound to it with a piece of strong wire. When the strand is stretched out straight and kept a little taut, one turn of the brace for each foot of the total length of the strand will produce an evenly twisted cable. — E. F. Koke.

��An Electric Alarm Signal for the Fisherman

WATCHING a fish-line set in the ice, on a bitter cold day is disagree- able, so that the following plan will be welcome. The usual "tip-ups" and "jumping-jacks" ser\^e their purpose nicely, but a more elaborate and interest- ing device is an electrical signal. A complete outfit may be carried in a box, as easily as a tackle. An ordinary, electric door-bell is mounted in a box, and put in circuit with a three-cell flashlight battery. Two strips of spring brass are tacked to the outside of the case. These are also connected, one with a terminal of the battery and the other with a binding-post on the bell. The strips of brass are bent in such a way that a slight pressure on one

���When a fish is hooked, the tug on the line causes the contact which rings the bell

immediately brings it into contact with the other. The bo.x is opened, and set near the hole where the fishing-line is led into the ice. One end of the string is tied to one of the brass strips, and as soon as a fish is "hooked" he will tug at the string and bring the strips together, sounding the alarm until removed.

�� �