The Tower Clock: Designed and Made for the University of Chicago by the ... by Earl Bixby Ferson

Author:Earl Bixby Ferson
Language: eng
Format: epub
Publisher: [s. n.]
Published: 1903-03-25T05:00:00+00:00

• MS

VERSITY OF CHICAGO.

THE TOWER CLOCK FOR THE

UNIVERSITY OF CHICAGO.

35

exactly perpendicular, in order to avoid the loss of motion, and therefore of regularity of time, which will occur if the angles of obliquity are not equal.

The hands are made of copper, elliptical in section, being made up of two circular segments brazed together at the edges, with internal diaphragms to stiffen them. The minute hand is straight and perfectly plain, with a blunt point.

At the center of the dial the width of the minute hand is one-thirteenth of its length, tapering to about half as much at the point.

The hour hand is about the same width, ending just short of the dial figure and terminating in a palm or ornament. The external counterpoises are one-third the length of the minute hand, and of such a shape that they will not be confounded with either of the hands; a cylinder, painted the same color as the dial, makes a good counterpoise. This counterpoise may be partly on the inside of the dial if it is desired to keep it invisible, but it should not be omitted, as it saves a good deal of power, prevents the twisting of the arbors, and also assists in overcoming the action of the wind on the hands. Two-thirds of the counterpoise weight may be inside.

The diameter of the dials and the weight of the bells are the two most important factors in the design of a clock.

This clock was designed, as the specifications show, for four dials of 12 feet diameter and an hour bell of 7,000 pounds. A9 it is not yet known in what tower the University will set the clock, and therefore the height of the dials above the ground, the mechanical parts are designed for a 15 foot dial.

The diameter of the dials should not be less than one-tenth of their height above the ground, so the limit of height for a 15-foot dial should be 150 feet.

The figures and minutes together will take up one-third of the radius of the dial; the figures two-thirds of this, or two-ninths of the radius, and the minutes two-thirds of

the remaining one-ninth of the radius, with every fifth minute more strongly marked than the rest.

How many of the thousands of people who pass daily up and down Michigan avenue, do you suppose have ever noticed, or if they have noticed it once, have ever thought of it again, that the clock face on the Kimball Company's tower has the name of the company instead of the numbers, to indicate the hours? In several towns in New England I have seen the words Memorial Gift distributed round the dial, and in one case the name of the giver was used for the same purpose. In Toronto, Canada, I passed the big 22 foot dial on the City Hall clock fully 25 times before I noticed that there were no figures or letters of any kind but only 12 broad flat surfaces about the width of

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