. Supplement to Spons dictionary of engineering, civil, mechanical, military, and naval. e spacebetween them ; only the upper plate is shown in the plan, Fig. 1205. B is a square box soldered tothe extremity of the plate B, and E is a small bar fixed to the box B, but isolated from it, andcarrying an adjustable contact screw E. By means of this screw the range of the tell-tale is head is milled with 120 teeth, and each tooth represents a quarter of a degree of temperature, ELECTEICAL ENGINEEEING. 589 so that an interval from a fraction of a degree to several degrees Centigrade, m
. Supplement to Spons dictionary of engineering, civil, mechanical, military, and naval. e spacebetween them ; only the upper plate is shown in the plan, Fig. 1205. B is a square box soldered tothe extremity of the plate B, and E is a small bar fixed to the box B, but isolated from it, andcarrying an adjustable contact screw E. By means of this screw the range of the tell-tale is head is milled with 120 teeth, and each tooth represents a quarter of a degree of temperature, ELECTEICAL ENGINEEEING. 589 so that an interval from a fraction of a degree to several degrees Centigrade, may be at willadjusted, between the contact poiut of the screw and the spring platinum contact F, attached tothe free end of the bare zinc, according to the degree of sensibility required in the apparatus. Thebare zinc carries at its extremity a metal piece which has two spring contacts, which are intendedto make contact with the screws E and M, when the bare plate expands far enough. M is asmall insulating bar supported by the base board D, and carrying the second regulating screw M,. which is added to the apparatus as a second tell-tale of the old sort, namely, with a fixed maximum,determined beforehand. It has fifty teeth round its head, each representing a degree screws E and M are connected by wire with the terminal P, to which is led one pole of abattery, and the fixed ends of the zinc plates are also connected by wire to the terminal N, to which isled the other pole of the battery. When the bare plate expands sufiQciently far to carry the spring intocontact with the screw E the battery circuit will be completed, and a local gong in the circuit are small spring ratchets gearing in the teeth of the screws E and M, and holding the latterin their adjusted positions. All the contact points are faced with platinum, to avoid oxidation, andthe whole is enclosed in a protecting case to exclude the dust of even the foulest use the screw
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectenginee, bookyear1879
