Simplex wiring slide chart
Date: patented 1905
Inventory Number: 1998-1-1391
Classification: Slide Rule
Dimensions:0.1 × 11.3 × 7.5 cm (1/16 × 4 7/16 × 2 15/16 in.)
DescriptionSlide chart composed of a white celluloid (?) disc attached by a brass fastener to a white celluloid rectangle. Printed with black and red ink.
Directions for the slide chart's use are printed on the face of the chart, below the disc. Below the directions is the formula on which the slide chart is based.
The circumference of the disc is printed with several scales. The outermost scale, printed in black ink, is for "DISTANCE IN FEET," and carries values from 5 to 10,000. Inside this scale two other scales, for "SIZE," are printed in red ink. Around approximately two-thirds of the circumference of the disc is printed a size scale in "BROWN & SHARPE GAUGE," with values descending from #16 to 4/0. Around the remainder of the disc is a size scale in "CIRCULAR MILS," carrying values from 250,000 to 2,000,000.
Printed around the disc are two additional scales. The innermost scale, for "VOLTS LOST," is printed in black and carries values from .5 to 1000. The outermost scale, printed in red, is for "AMPERES" and has values ranging from 5 to 10,000.
Printed in the top left-hand corner of the chart's back are circular millage ratios, for use in converting among circuits with different numbers and types of wires. A table listing the decimal equivalents of 32nd inches is printed along the right edge of the chart's back.
The remainder of the back of the chart is taken up with a table listing the area, diameter, weight, volts lost, amperes of different sizes of wire.
Signedface, center of chart: WIRING / RUBBER INSULATED / SIMPLEX / WIRES AND CABLES / COMPUTER / COPYRIGHTED
face, bottom: THE WHITEHEAD & HOAG CO. NEWARK, N.J.
back, top center: THE:SIMPLEX:ELECTRICAL:CO. / RUBBER INSULATED WIRES AND CABLES / 110 STATE STREET, - - BOSTON / WESTERN OFFICE, 1146 MONADNOCK BLOCK, CHICAGO.
back, bottom center: SIMPLEX
Inscribedface, bottom right: PAT. JUNE 6, 1905.
back, bottom left: AERIAL—UNDERGROUND—SUBMARINE / HIGH OR LOW TENSION / LIGHT—POWER
back, bottom right: BRAIDED—LEAD COVERED—FLAME PROOF / Single or Multiple Conductors / TELEPHONE—SIGNAL—TELEGRAPH
FunctionFor use in determining the size of conductor wire, volts lost, current, and distance from supply to distribution points in a circuit.
To determine the size of conductor wire necessary in a given circuit, the user first rotates the disc such that the appropriate value on the distance scale (disc) coincides with the appropriate value on the volts lost scale (chart). Then, holding the disc in place, he locates the appropriate value on the amperes scale (chart). The coincident value on the size scale (disc) indicates the wire gauge required. For circuits other than two-wire circuits, he transforms the size value found according to the table on the back of the chart.
In the following calculations, for circuits other than two-wire circuits, the user first transforms the circular millage of the conductor wire according to the table on the back of the chart.
To determine the volts lost, the user first rotates the center disc such that the appropriate value on the size scale (disc) coincides with the appropriate value on the amperes scale (chart). Next, holding the disc in place, he locates the appropriate value on the distance scale (disc). The coincident value on the volts lost scale (chart) indicates the loss of voltage over the circuit.
To determine current, the user first rotates the center disc such that the appropriate value on the distance scale (disc) coincides with the appropriate value on the volts lost scale (chart). Holding the disc in place, he locates the appropriate value on the size scale (disc). The coincident value on the amperes scale (chart) indicates current strength.
To determine the distance from supply to distribution points, the user first rotates the center disc such that the appropriate value on the size scale (disc) coincides with the appropriate value on the amperes scale (chart). Then, holding the disc in place, he locates the appropriate value on the volts lost scale (chart). The coincident value on the distance scale indicates the distance from supply to distribution points.