The special purpose of this paper is to furnish the table of original data 1 : hat has been compiled by the late Dr. S. Fujiwara, so that research workers of this interesting subject may have at hand the valuable material for further investigations. This is facilitated by the recent publication of Fujiwara's work, in which the writer edited, which concerns itself especially with the tabulation and graphical representation of freezing dates of Lake Suwa in the Central Japan. Freezing dates of Lake Suwa have been kept by Suwa shrine, Yatsurugi temple, Mr. Y. Suwa and others. More recent freezing dates are kept at the Suwa weather station. The characteristic ruptures or “Omiwatari” occurring usually two or three days after the full freeze of Lake Suwa which was covered with ice are shown in photographs (see annexed plates). To show climate history, sequences of freezing dates of Lake Suwa may be tabulated as a chronological table. The dates of freezing and “Omiwatari” for Lake Suwa are given in chronological order. We are convinced that these historical data extending over more than 5 centuries are often remarkably exact : they constitute a unique and valuable source of climatology. The periods, 1444-1682 and after 1924 to the present, include the observations relatively homogeneous among themselves, having a sufficient degree of accuracy. The period, 1683-1923 contains the data, which are much inferior to modern or older observations and are regarded only as supplementary, but still they can serve. For example, we find for 1443/1444 winter noted as follows : The freezing date, January 7, 1444 and “Omiwatari” date, January 9, 1444. This list shows at a glance the approximate character of all winters for a period of five centuries, except only few winters (1457/8, 1594/5, 1682/3, 1824/5 and 1864/5). Thus the freezing dates of Lake Suwa as phenological indicator immediately provide the source for a 500-year chronology of winter temperature. The early records of Lake Suwa clearly show a long period (14501700) much colder than the average. The years since have been characterized by warmer winter (i.e. later freezing) even through there is a definite sequence of fluctuation between cold and warm. The frequency of mild winters in the last 21/2 centuries is a striking phenomenon that it has been noticed by many climatologists.
The author explains theoretically the relation between natural steam and underground water, and also the limitation which the steam is able to distribute under the ground. As the natural condition of under ground is very complex as to its fissures, the author showed the data of Unono hot spring in Kagoshima Pref., Unzen in Nagasaki Pref. and elsewhere, and then he supposed the structure which natural steam is distributed.