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Above reasons refer exclusively to the aneroid of the new apparatus. Touching the cyclonometer, it is super-fluous to enlarge on the practical advantages which the mariner may derive from it, principally in his voyages onthe high seas. Whoever reads this pamphlet may judge for himself of it. All we claim is to offer him, as it were,a guide, simplifying the apparatus so that he can manage it even in cases when the manifold attentions to diversemaneuvers and the anxiety and confusion which usually accompany the imminence of danger do not permit com-plicated calculations.

The first of the reasons mentioned above is to-day certainly stronger than ever before. For,since these Islands have come into the possession of the United States of America, navigation onthe seas to the north and east of Luzon has vastly increased, and consequently an instrumentwhich to the merit of Father Faura’s barometer adds the incomparable advantage of being applicablewith the greatest facility to different latitudes throughout the Far East must be highly appreciatedby mariners.

The documents requesting from the Spanish Government the privilege of importation andpatent of the instrument for the Philippines were lost, owing to the disturbances in this Archi-pelago. Imitations of the instrument can not therefore be now legally prevented. It lias beenconstructed in London and in Germany, the indications on the rim having been translated intoGerman.

The barocyclonometer (PL XXXVII) 1 .—As its name suggests, the barocyclonometer is a com-bination of a barometer and of a novel contrivance which we have named cyclonometer. As theinstrument is actually constructed it also comprises a thermometer, showing the temperature inboth Fahrenheit and Centigrade degrees, but, although this addition augments the convenienceof the apparatus, it is none of its essential parts.

I. The aneroid barometer (PI. XXXVIII.)—The barometer, which if it is to meet require-ments must be a first-class instrument, has some remote resemblance to the barometer of Fr. Faura,on which it is based, but differs from it in several important points. The face of the aneroid exhibitsthe double graduation corresponding to the millimeter and the inch scale, respectively, of the mer-curial barometer. Around this face is laid a flat ring of silvered brass about 23 millimeters wide,which, being attached to the rim that holds the cover glass, can be made to revolve around thedial by turning said rim. The divisions and legends engraved upon this ring bear no relation todefinite lines of the graduation. Those of the upper half, however, correspond to the groups “fairweather,” “change,” “unsteady,” or “stormy weather” of the ordinary aneroid for popular use, whilethe fact that the ring can be turned about the center of the face constitutes the adaptability ofthis barometer to different latitudes and to the various seasons of the year. The data necessary foreffecting this adjustment are engraved on the lower half of the ring itself.

(1) The first group.—“Fair weather,” “settled” occupies a considerable portion of the first quad-rant, its limits toward the right being as vaguely defined as those of the group “unsettled” or“stormy”'—“typhoon” toward the left. Since for the Philippines the lower limit of pressure duringvariable weather lies between 755 and 756 millimeters (29.73 and 29.76 inches) and the width ofthis group is 4 millimeters (0.15 inch), the lower limit indicating “fair weather” will vary between759 and 760 millimeters (29.88 and 29.91 inches). The group “fair weather” is automaticallydetermined by setting the index for variable weather as will be explained forthwith. (See 2.)This division also gives the directions of the win'ds which usually prevail when the barometerneedle indicates high pressure—that is, north to east in December, January, and February, andeast to south during March and April. The northeasterly winds commence already in November.In February they draw more to the eastward, while in March and April we have southeasterlywinds. Experience teaches us that they are all the steadier the higher the needle points. Thenorth to east winds of the period November to February drive to the eastern coast of Luzon massesof clouds from the ocean, where they have been formed in consequence of the ascending aircurrents during the daytime. These clouds condense and are the source of rain on the east coast,

1 Another form of the barocyclonometer (aneroid and cyclonometer in separate boxes) is shown on PlatesXXXVI11 and XXXIX. In this case the thermometer is inserted on the face of the aneroid.