In the report of last year reference was rüade to the proposed undertaking 

 of a series of rueasnrements of earth temperature, liy means of the thermo-electric 

 method. The labor of determining, experimentallj', the best method for accom- 

 plishing this end was undertaken by Mr Hiraoka, Lecturer in the Department of 

 Physics, and lie has worked with great industry to overcome the difficulties 

 which seemed to be in the way. Unfortunately complete success in that direc- 

 tion cannot yet be recorded. The chief and, apparently, only difficulty seems 

 to be to secure sufficiently perfect insulation of the wires leading to the thermo- 

 electric couples. It will be remembered that the ordinary means of insulation 

 are not procurable in this country, or, if at all not without great difficulty. 

 Various devices have been resorted to and in some instances success seemed 

 assured, very satisf\xctory tests being obtained ; but after a few days the insula- 

 tion has broken down and temperature observations, therefoi-e, rendered impossible. 

 Success is by no means dispaired of, however, and efforts to secure it will still 

 continue. 



Reference was also made in the report of last year to a series of experiments 

 about to be imdcrtaken for the detenuination of the velocity of sound. It was 

 proposed to take advaritage of the signal gun, fired at 12 m. each day from 

 Tenshudai and of the telegraph line connecting the observatory with the 

 University. By tlie aid of the latter the time of the arrival of the sound at 

 each of these points is recorded upon a chronograph in the physical laboratory 

 at the University. This plan lias been successfully carried out and observations 

 to the number of more than two hundred have been already secured, giving the 

 velocity of the sound wave under widely varying meteorological conditions. In 

 addition to these, made, one each day, by means of the noon signal gun, a large 

 number have recently been made, by means of successive firings upon the same 

 day and, as nearly as possible, under the same meteorological conditions. These 

 will greatly increase the value of the regular series and in the end, a result of 

 considerable accuracy ought to be obtained from the reduction of thes observations. 

 It has been thought best, however, to publish these results in a separate memoir, 

 hence they do not appear in this report, as might be expected from what was 

 said concerning them in tlie last. 



A suggestion was also made concerning the use of some form ol' seismometer 

 orscisniograjih in the meteorological observatory. Early in the year 1880 interest 

 in seismology, (piickened, doubtless, by the xuiusually violent earthquake of 

 February 22, became so great that a society was formed in T'okio known as the 

 " Seismological Society of Japan." 'J his society is in good working condition. 

 It has already publi.shed volumes of its.i)roccedings amUit is looking well after 

 the interests of seismology in this country. It is desirable, therefore, that all 

 oliservers co-ojierate with tlie society and it would be extremely useful to have 

 one or more seismometers or seismographs, of a Ibrm which shall be a|i[M0ved by 

 this society, placed in tlie meteorological observatory. For instruments which 

 are not self-recording, or for those reiiuiring frequent observation or attention. 



