. Electrical world. se of heat supplied fr^m the cathode. New Telephone Patents. If the general activity in any field of industry may be measuredby the activity of its inventors, then truly must telephony be in aprosperous state, for we have at hand this week for considerationan extraordinary number of telephone patents. These treat of agreat variety of subjects, as might be expected, but for conveniencethey will be grouped together under topical headings in so far aspossible. The first group will include patents bearing on centraloffice apparatus. CENTR.^L OFFICE APP.^RATUS. The heat coil or
. Electrical world. se of heat supplied fr^m the cathode. New Telephone Patents. If the general activity in any field of industry may be measuredby the activity of its inventors, then truly must telephony be in aprosperous state, for we have at hand this week for considerationan extraordinary number of telephone patents. These treat of agreat variety of subjects, as might be expected, but for conveniencethey will be grouped together under topical headings in so far aspossible. The first group will include patents bearing on centraloffice apparatus. CENTR.^L OFFICE APP.^RATUS. The heat coil or sneak current protector forms the subject of threepatents. These all apply the same principle, viz.: the shortness offusible metals w^hen slightly heated. The application of the prin-ciple is, however, made in tw-o different ways. In Fig. I is shownsectional views of all three new coils. At the right is a heat coil patented by M. Setter, of Chicago. Aswill be noted, on one end there is a hinged plate to which a stud. FIG. I.—TELEPHONE CUT-OUTS. is attached. Normally, a ring of fusible metal encircling projec-tions from the pieces b- and b^ holds them together. In this condi-tion the coil is adapted to be mounted in a spring holder whichstrives to pull the ends apart. When an abnormal current passesin the circuit, which is led through the heat coil, from one terminalbutton to the other, the heat generated so affects the solder ring, b^,that its tensile strength is impaired and it breaks. The hinge atonce opens, giving, as it does so, an inclination to the stud, b^. suchas to cause it to escape from its holder and thereby breaking thecircuit, which at once becomes grounded against the stop for thespring terminal. The other two heat coils cause a shearing ofsolder under exactly similar circumstances, to effect an operationof the switching members. One of these is shown at the middleof Fig. I, while the other, together with a mounting suitable foreither, is shown at the left. In
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectelectri, bookyear1883
