instrument—that is, on board of ships under way ? We are far from claiming for the barocyclono-meter a usefulness which it does not possess. We do not recommend its use for determining thedirection in which the storm is moving by means of the “third approximation” as long as the ship,steaming on her course, finds herself in zone A. The vessel’s speed may be considerable comparedwith that of the storm’s advance, and it might easily happen that, owing to the course of the shipand the distance covered, the small needle pointed in a seemingly entirely wrong direction—as eachone may easily ascertain for himself by means of a few pencil lines. But with the vortex at such adistance as the ship’s position in zone A implies it suffices to know the direction in which the centerlies, the approximate distance of the center and, in a general way, whether the combined effect of itsmovement and the ship’s course and speed brings the observer nearer to the vortex or not. Thetwo latter points can be learned from the indications and behavior of the barometer; the former,with great reliability, from the wind disk. Prom both together a fairly good estimate can be formedof the direction of the trajectory.

The case is, however, different in zone B, and especially in zone C. There the ship will rarelymake much headway while the rapid veering of the wind will allow of making the third approxima-tion at short intervals, so that the place of observation will be but little displaced during the interval,although some allowance should always be made for the ship’s course and run.

When applying the barocyclonometer for the purpose for which it has been designed the observermust bear in mind the sound advice concerning the use of this instrument given by Pr. Proc, S. J.,in his memoir on the “De Witte Typhoon” of August 1-6, 1901:

To finish, we will answer a question which has been put to us by several officers, who, at anchor during thetyphoon, took advantage of its approach to study the indications of the barocyclonometer, an instrument of some-what recent use, constructed and perfected by Rev. Father Jos§ Algu6, Director of the Manila Observatory. Thisinstrument is really very valuable, and may be of most signal service at sea if handled by a practiced observerand read with an experienced eye. One must, however, never forget that like any other apparatus constructed forgeneral requirements, the indications it gives are based upon means, that consequently they may not, in excep-tional cases, be taken literally and rigorously, but need, in such circumstances, to be fitted to particular wants.Thus used, the instrument gives useful information, but it would be excessive there to seek a guide for particularsin the study of exceptional cases.

We shall therefore say of it what must be said of all the most perfect instruments of navigation: It is wellworth recommending to captains, but neither this nor any other instrument will dispense the commander of a shipto appeal to his experience. This is the most valuable of all instruments, which must never be locked up, particu-larly when it has been acquired, increased, and enriched by ten, fifteen, twenty years and more of sailing in thesame parts, and of conscientious, diligent observation. For a captain thus qualified, certain small signs, insignifi-cant for anyone else, and which it would even be difficult to explain in a general treatise, may give more reliablewarnings of the danger than all those that are met with in the best books. Thus the barocyclonometer is a greatprogress, but it requires commentaries and explanations. We will here only mention one point on which someseamen may have been led astray, namely, the direction of the wind in certain parts on the approach of cyclones,and, to speak of the regions best known to us, we shall limit ourselves to the mouth of the Yangtze-Kiangbetween the group of the Chusan Islands and the old bed of the Hoangho.

It is almost a rule that, each time a typhoon approaches, particularly when it comes to strike the coast to thesouth of Ningpo, the bearing of the wind grievously leads in error those who witness the phenomenon for the firsttime. Keeping to the study of the typhoon of August 3, let us take the report of Zi-ka-wei, printed in the appen-dix, or that of the North Saddle Island light-house, which is situated farther off. We shall find, at the Observatory,winds (and we may add clouds) coming from the east, and at the light-house continual breezes from east-southeast, force 6, 7, and even 8—that is, typhoon winds—during the whole day, on the 2d, on the 3d, not onlywhen the typhoon landed on the coast, almost right to the south, but at the time when it was clearly in the south-southeast and southeast between Formosa and Nafa.

The explanation which we give without development is twofold. In the first place, the apparent anomalyresults from the shape of the isobars, which, far from keeping to the circular or even elliptical shape, assumealong the coast undulated, tortuous, and apparently most capricious contours, though all submitted to laws whichwill some day be formulated.

The second cause of the deviation of the wind, which is not without influence upon the deformation of theisobars, is the call of air taking place generally in summer from the sea toward the overheated plains situatedon the continent to the northwest and to the north of Shanghai (Western China, Mongolia, and Chili). The airput in motion by the typhoon ought to incline to northeast or at most to east-northeast. On the other hand, ongetting near the coasts it finds a slope and a certain attraction which ought to make it flow from south-southeastor from southeast. As long as the typhoon’s vigor has not entered into the period of violence, close to the center,