THE RAROCYCLONOMETER

DESCRIPTION OF THE BAROCYCLONOMETER.

Although it can not he denied that there exists a certain relation between the height of thebarometer within the body of a cyclonic storm and the distance of the vortex, still the reading of thebarometer does not give us any information with regard to the direction in which the center is mov-ing, information which is frequently of the greatest importance to the observer, especially if thelatter is a sailor. Fortunately, we can obtain this knowledge by applying the laws of cyclonic cir-culation to the observed direction of the prevailing wind. Hence it follows that if, by combiningthe typhoon indications given by the barometer with those derived from the direction of the wind,we could reduce them to a practical method by means of a simple mechanical instrument, wewould have an efficacious means of reassuring us at the first signs of a typhoon. This has been ouraim in inventing the apparatus which we have called the “barocyclonometer.” The present chap-ter deals with the description of the instrument and the scientific principles on which each part ofit is based, leaving for the next the use and management thereof.

Necessity of such an instrument.—In the preface of a descriptive pamphlet on the barocy-clonometer published by this Observatory in 189 8 I wrote:

Two reasons mainly induced me to procure tlie construction of the new apparatus which is described in thispamphlet. The first was the great convenience, not to say necessity, of a barometer which could be used indis-criminately in all the latitudes of the Far East, especially now that the exigencies of traffic and commerce on theone hand, and the manifold complications of an international character on the other, open each day new courses tothe frequent navigation of our mariners of the Navy as well as of the merchant marine. Moreover, since in theseseas the meteorological elements present such different characteristics that the navigator sometimes in a singlevoyage finds normal barometric heights as diverse as 754 and 758 millimeters in the short distance which sepa-rates Hongkong from Manila, and 771 and 759 millimeters between Chefoo and Iloilo, it is quite impossible inthese cases to apply the fixed readings which are commonly engraved on the faces of barometers. Even the bestof them have this defect, as, for instance, the barometer of Father Faura, which consequently is applicable onlyto the limited zone of our Archipelago. Add to this that in the seas of this Far East the barometric height limitof the outermost zone of the typhoons, a datum of capital importance, fluctuates between very different values,being 765 millimeters for the twenty-fifth to the thirty-second parallels of north latitude, and 756 millimeters forthe tenth to the sixteenth parallels of north latitude during the winter months. For which reason it is impossiblefor the mariner to navigate securely and to forestall the danger of such terrible meteors by using a “commonreading” in seas where the extreme barometric heights of the body of the cyclone differ normally more than 8millimeters. How this difficulty has been obviated in the aneroid the reader will see in the course of this work.

The other reason, of no less weight, is the sad fact that the growing popularity of Father Faura’s barometerhas induced some manufacturing firms to imitate said aneroids, but—in order to profitably meet industrial com-petition—in such a way that frequently the observer, instead of finding in them an accurate and trustworthyinstrument, as would be right, finds in his possession a mere hardware toy which would be capable of discreditingFather Faura’s good arrangement of the indications and readings engraved on the face thereof, if its fame werenot so justly established. Several times we have heard Father Faura lament this pernicious abuse, which, unfor-tunately, has no remedy. Now that the advisability is recognized of offering to the public a new apparatus which,on account of being universal, may be used also in other latitudes than those of our Archipelago, we shall fromthe very beginning make sure of the most important point, which is the fidelity of the instrument, so that personswho wish to have the quality of their barometer guaranteed can have it. 1

1 The construction of this instrument has been intrusted to the firm G. Lufft, of Stuttgart. The barometerand the cyclonometer are also constructed separately, in order that those who use Father Faura’s barometer, whichis so popular in this Archipelago, may complete it without great expense by simply procuring the cyclonometer.

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