Zikawei Observatory.—Typhoon Highways in the For East. By R. F. Louis Froe, s.J., Member of the Shanghai Meteorological Society. No. 1. Across the South end of Formosa Strait. (Zikawei. Printed at the Catholic Mission Press, Toustwé Orphan Asylum. 1896: 4to, Pages 40, Pi. 5, Figs. 5.)
The title of this work would seem to show that the aim of the author is to determine the paths usually followed by the typhoons in the Far East. But in reality the title does not express exactly the mind of the author. The following is how he exposes his intention himself in the preface:
desire to analyse successively in different essays,... each of these paths or rather portions of the paths in order to discover the dangers and to watch closely the behaviour the storms assume therein. I shall select in each series, a cyclone, usually the most recent, to investigate it more at leisure; then reviewing the principal typhoons which have visited the same places in analogous circumstances, I shall attempt to deduce therefrom some points of general information."
It is then not merely monographs upon one or several typhoons that the author intends to gre to the public. Convinced, however, that such monographs are and will be for a long time to come not only useful but of absolute necessity, since they are to serve as a basis to any attempt at building up theories, and to all investigation of the laws which tule these meteors, Rev. Father Froe begins by giving in a first chapter a detailed study of the typhoon which crossed on the 19th of last September the south of the Formosa Channel. This study made upon important original documents furnished ty the 2. Gotmnien of the HI. M Ca., "hales and Victoria and H.M. ships Peacock: and Pique, and several other steamers and the meteorological stations of the I.DI.C., is well conducted and enables us to follow the storm in its successive phases. Not only is the trajectory clearly determined but the form and the extent in] of the meteor is carefully examined.
The level* of the cyclone and its variations as it advanced towards the China coast are fixed in such a manner as to leave no. room. for the least doubt. The author gives two kinds of variations of the level, the one which he calls the spasms of the storm" is shown by rapid oscillations of the top of the mercurial column, and would be due according to the author "'to oscillations of the lower point effected along the axis in the vertical direction." The other variation is the continuous filling up of the level at the contre of the typhoon; the author shows clearly that during the passage of the typhoon from Takow to Swatow the barometric pressure increased at the centre of the typhoon. The form of the gradients around centre is brought to evidence by tao woodcuts giving the vertical sections of the cyclone, relatively two perpendicular planes of which one is parallel with the coast of China. The two plates would have been clearer and more instructive if the author had divided the lines of abscissae into nautical miles from the centre of the typhoon. The mere indication in a footnote that a nautical mile on this abscissa is equal to 0.42 millimetre is not satisfactory. The section following a plane parallel with the China coast is particularly interesting and of the highest importance for the correct understanding of the observations made in the north of the channel. It alone explains the behaviour of a barometer at the north of the channel when a typhoon crosses the south, and enables one to gather from this instrument the precious indications which it can furnish to those who can, understand them, In a second chapter the author gives a summary statement of the 17 typhoons which from 1877 to 1894 had followed a path almost identical to that of the typhoon of September 19, 1895. These statements are drawn from original documents and especially from the publications of the Zikawai Observatory. In these resumes the author has done well, in my opinion, in keeping above all tothe traits either of contrast or of resemblance between these different typhoons. Two charts exhibit the trajectories of these 17 typhoons. The first of these charts contains the trajectories of the typhoons crossing the South of the channel in July and August; the second contains those of the typhoons which effected this passage in September. Though there be a family likeness between these trajectories, how this subdivision into two groups is quite natural. The typhoons of Riecaber all deflect. more Westward, and those of July and August more North-westward.
After having thus in these two first chapters placed before the reader what might be called the documents of a suit, Rev. Father Froe arrives at the conclusions, To draw conclusions is not, us is easily understood, the easiest nor the lerist important task, The author divides his conclusions into two parts; conclusions of practical order, and conclusions of a theoretical order.
In the conclusions of a practical order, after having brought forward the division of the trajectories into two groups to chieh allusion was made above, and after javing established the relative frequency of these typhoons during the three months of duly, August, and" September, Rev, Father Froe examines the characters of these typhoons and finds that generally they make their appearance almost suddenly, that they are very narrow, violent, and even sometimes formidable, and that they move with a velocity on an average of 13.1 miles per hour. In general a central calm is observed there and the winds in the body of the typhoon itself have a well-marked and unmistakable convergence. The typhoon of 1895 investigated by Pere Froe gives 12 points as angles of the direction of the wind with the radius going to the centre of the cyclone. "This figure 12 points," says the author, "at which I arrived for the typhoon 1895 is the same which Father Chevalier had found in 1892." The author handles next the important question of the forewarning signs by which the presence of these typhoons can be detected. Three concise tables, which must have required a great deal of work, drawn up with care and ability, allowed him to establish some laws on the duration of the fall of the barometer at a station before the advent of the body of the typhoon itself, then rior to the centre of the typhoon, and the Interval between the first bursts of the The barometric height at the centre of cyclone is called the level of the cyclone.
Text read from the printed page and cleaned; old type leaves the occasional error.