(No Model.)

B. WESTON. ELBGTROPLATED COIL FOR ELECTRICAL MEASURING INSTRUMENTS. No. 392,885. Patented Nov. 6, 1888.

g IIVVEIVTOR- I B) SATTOR/VEY,

Nv PETERS Phowumu hcr, Washingficn, 11.0v

UNITED STATES ParaN'r EDWARD WESTON, OF NEVARK, NEW JERSEY, ASSIGXOR TO THE XVESTON ELECTRICAL INSTRUMENT OOliIPANY, OF SAME PLACE.

ELECTROPLATED COIL FOR ELECTRICAL MEASURING-INSTRUMENTS.

SPECIFICATION forming part of Letters Patent No. 392,385, dated November 6, 1888.

Application filed April 9, 1888. Serial No. 270,093. (No model.)

To ctZZ whom it may concern.-

Be it known that I, EDWARD iX nsrorv, of Newark, Essex county, New Jersey, have in vented a new and useful Improvement in Electroplated Coils for Electrical Measuring-Instruments, of which the following is a specification.

My invention relates to a coil which in certain electrical measuring-instruments is sup- 1o ported so as to move freely in a magnetic field, and through which a current to be measured is passed. The passage of the current causes a movement of said coil against a uniform rcsilient resistance, and the strength of the cur- 1- rent is indicated by the extent of movement of said coil.

In another application for Letters Patent, filed on the 17th day of March, 1888, and se rially numbered 267,47i,l have fully described an apparatus wherein such a coil is used in the manner described.

My present invention has more particular reference to the construction of said coil and to the covering or envelope thereof, which is 2 of diamagnetic metal. It is a well-known fact that when a body of diamagneticmetalsuch as copperis suspended between the poles of a powerful magnet it finds in the field of force a powerful resisting medium which opposes 0 any motion of the metallic mass and speedily brings it to rest. To this end I inclose my coil in a mass of copper, and so render theneedle or pointer attached to the coil and indicating the extent of its motion deadbeat or free from undue oscillation or vibration. While this envelope of copper may be applied to the coil in the form of plates soldered or otherwise secured together, I find it very much more advantageous and convenient 0 to deposit the copper on the coil by electroplating,because in this way I can produce a perfect envelope withontjoints of homogeneous metal, which by simple manipulation of the electrode in the plating-bath I can deposit in 5 a thick mass atone point or a thin mass atan' other, as may be desired.

In the accompanying drawings, Figure l is a face view of my coil havinga covering of electro-deposited metal, part of said coil and envelope being shown'in section on the line :t

at of Fig. 2. Figs. 2 andS are sections of my coil on the lines 3/ y and of Fig. 1, respect ively. Fig. 4 is a vertical transverse section of a coil having only an outer peripherical covering of eleetro-deposited metal. Fig. 5 is 5 5 a similar section of a coil having only an inner covering or coil of electro-deposited metal. Fig. 6 isa perspective view of a coil having only side or face pieces of electro-deposited metal.

Similar letters of reference indicate like parts.

A is the coil of insulated wire, which may be of any desired form. It is here shown as quadrangular. The exterior of this coil is 6 5 covered with electro-deposited copper to form an envelope or covering, which may be regarded as consisting of an inside frame, 13, an outer frame, 0, and side or face pieces, D D. This envelope is in one piece, as here shown, and for the purposes of the electrical measuring-instrument referred to in my above-notcd application it comprises the parts before named; but it is to be understood that I do not limit my present invention to an electro- 7 deposited envelope covering the entire exterior of the coil, because I may for some purposes use only an inner frame, B, or an outer frame, 0, or only the side pieces, D D, in each case, however, producing the part of electro- So deposition. Thus in Fig. at is shown a coil having only an outer frame, C. Fig. 5 repre sents a coil having only an inner frame, B, or core. Fig. 6 represents a coil having only face or side pieces, D. So, also, I make the 8 coil with any two of these parts, as the frame 0 and side pieces, D, or frame 0 and frame or core B, or frame or core 13 and side pieces, D.

I may produce this electro-deposited covering by various methods, one of which I will now 0 specify, by following which any one skilled in the art will easily be able practically to make my invention.

I wind the coil upon any suitable form and permeate it with shellac or any other suitable adhesive material, whereby all the turns of wire are firmly fastened together. When the shellac is dry, I remove the coil from the form and dip it in melted beeswax, so that a film of wax is left adherent. Upon the wax I ap- 10o ply a coating of plumbago and then place the coil in any suitable electrodeposition, both arranged for copper deposit. In order to effect the deposition of the inside frame, one anode may be supported inside the coil, and generally the anodes are to be arranged so as to effect the deposition at the points needed to secure deposits of the desired continuity and thickness. Any one skilled in the manipulation of electroplating-baths will have no difficulty in making such arrangement.

For practical use I make the outer frame, 0, thicker than the inner frame, B, so as to secure the greater mass of diamagnetic metal on the outside of the coil, and hence in the densest part of the magnetic field of force surrounding the coil, by which means I obtain a more efficient retarding effect of the copper when the coil moves in the field.

It will be obvious that by producing the copper core, side pieces, or outer frame, or all of them, in this way, I obtain all parts of strictly homogeneous diamagnetie mctal,-and so secure uniformity of action thereof in the magnetic field. In delicate instruments of precision this is an important desideratum. So, also, I avoidpossibility of portions beingundulythiek or thin or more or less dense than others, and the necessity of any soldering or brazing or of cutting the parts to make a proper fit. The

terminals E of the coil are carried out through the outer frame, as shown.

I claim 1. An insulated conductor in coil form having an inner frame or core of clectro-deposited metal, substantially as described.

2. An insulated conductor in coil form having an outer peripherical covering or frame of electro-deposited metal, substantially as de scribed.

3. An insulated conductor in coil form having a face or side covering of electro-depositcd metal, substantially as described.

i. An insulated conductor in coil form wholly covered on its exterior with electro' deposited metal, substantially as described.

5. An insulated conductor in coil form having a covering of electro-deposited diamagnetie metal, substantially as described.

(3. An insulated conductor in coil form wholly covered on its exterior with electrodeposited diamagnetic metal, the deposit on the periphery of the coil being thicker than elsewhere, substantially as described.

EDWARD WESTON.

Witnesses:

BARK BENJAMIN, EDGAR GooDwrN.