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S. P. Fergusson
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S. P. FERGUSSON

Abstract

SYNOPSIS

Corrections, for instrumental errors, the temperature of the mercurial column and for latitude, must be applied before readings of mercurial barometers can be used to represent true atmospheric pressures. Obviously, each operation is a possible source of error, and a direct method of determining correct values is highly desirable.

In 1914, Col. E. Gold, of the British Meteorological Office, suggested a scale to be used with the attached thermometer, by means of which the corrections referred to can be obtained in one reading of the thermometer. This scale, however, can be used for but one pressure; in the present paper the author describes a modified scale from which the same corrections can be obtained for any pressure. The final corrected pressure is obtained in five or less operations instead of six required by other methods, the corrections can he read more accurately, and in addition to the time saved there is a saving of one column of entry in the record-form.

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S. P. FERGUSSON

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S. P. FERGUSSON

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S. P. FERGUSSON

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S. P. FERGUSSON

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S. P. FERGUSSON

Abstract

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S. P. FERGUSSON

Abstract

SYNOPSIS

An improved recording gage for precipitation.—This instrument records the weight of rain, snow, etc., falling into a suitable receiver supported by a spring balance. The original instrument of this pattern was designed by the author in 1888, the present improvements consisting of a more compact balance mechanism, whereby the movement of the receiver is more nearly rectilinear, and a device for obtaining two or more traverses of the record sheet by the pen; improved accuracy and greater capacity are secured in this way without increasing the dimensions of instrument. The record sheets require changing only after each rain, whether of one or several days duration, and the accuracy of registration can be checked by measuring the amount of rain in the standard raingage. The instrument is of simple, rugged construction in order that it may function properly under severe conditions and can be exposed in any place suitable for the standard raingage.

A new registering raingage for isolated stations.—In isolated regions of excessive moisture and large rainfall, where the conditions do not favor the use of recording gages, an instrument that will register daily, weekly, or monthly totals will be useful. The apparatus described accomplishes this result by means of a clock-driven funnel which moves successively over any described number of receivers arranged in a circle. The clock, preferably of the form described in this paper, is intended to function, with one winding, during any period of time desired, to a maximum slightly exceeding one year. Evaporation is prevented by a layer of oil over the water collected in the receivers.

A new long-period clock for recording instruments.—Long-period lever clocks have been objected to for the reason that friction is supposed to be greater and more variable in trains having a large number of mobiles than in the well-known daily, weekly, or monthly clocks. Since the only important consideration is that of maintaining the power during the period through which the clock should run, excessive variability of friction can be avoided by the use of an elastic train composed of a complete watch or clock whose mainspring is driven or kept wound by a heavier spring-driven motor, as illustrated and described. A movement of this kind is simple, comparatively inexpensive, and easily kept in good condition.

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por S. P. Fergusson
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S. P. Fergusson

Synopsis

Records of gustiness or rapid variations of velocity, usually obtained during gales, are important in studies of destructive effects of high winds, and from these data the relation of variations of high frequency to high mean velocities during long periods of time has been determined with fair accuracy. Gales, however, accompany but one or two kinds of condition, and a desirable supplementary comparison of gustiness with other phenomena of the atmosphere—storms, cloudiness, diurnal changes of pressure and temperature, etc.—has been undertaken at Blue Hill Observatory under the very favorable circumstances of an unusual range of velocity, ideal exposure for instruments, and wide-scale continuous records of all elements.

Gustiness, by a highly-sensitive rotation anemometer, is recorded on paper moving 60 mm a minute during periods of about 20 minutes regularly at 8 A.M., 2 P.M., and sunset, and at other hours during unusual conditions. The rotor can measure five changes of velocity in one second and the time-scale of the recorder can be expanded to 40 mm a second when details are to be studied.

The records obtained so far confirm earlier data of the connection between variable velocities and the more conspicuous changes of condition of the atmosphere, the range of velocity and frequency of gusts being higher on days with strong convection than during other periods when the sky is overcast and the vertical component of the wind is small. Further study of records will be necessary to evaluate relationships not so obvious but possibly of greater importance.

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