June 5, 1913] 



NATURE 



;6j 



proof drawn from a series oi accurate measurements 

 of time, space, and mass which can be repeated at 

 will, so that the man oi science of to-day is inclined 

 by his traditions and training to set aside as unworthy 

 of consideration all phenomena which are incapable 

 ol treatment by the methods of precision and logical 

 proof. Experimental psychology, however, that can 

 measure rates of fatigue of memory, or persistence of 

 association, has been received into the fold of orthodox 

 natural science, and is making great progress towards 

 a better comprehension of the workings of the human 

 brain. 



But readers of M. Bergson's book, especially those 

 acquainted with "Matter and Memory," will recall 

 that M. Bergson looks upon the human brain merely 

 as a means of obtaining recollection, un organe de 

 rappel, not as the essential phenomenon of human 

 1 onsciousness or of the life of the mind. Thus by the 

 investigations of modern experimental psychology, we 

 learn more about the instrument of communication 

 between the outer and inner worlds — we do not extend 

 our knowledge of those worlds themselves. 



M. Bergson suggested that the function of the brain, 

 and indeed of the recognised senses, is to limit rather 

 than to extend the outlook of the mind. They become 

 the organs of attention to life, picking out and pre- 

 serving ready for use only those impressions and 

 recollections which will be serviceable to the life of the 

 individual or the species. Everything else is masked 

 and put away where, in normal circumstances, it does 

 not distract the attention of the participant from the 

 things which help him to accomplish his mission in 

 the world. But in certain circumstances, such .'is ill- 

 ness, shock, approaching dissolution of the partner- 

 ship between mind and body, the limitation may sud- 

 denly disappear, the barrier breaks down — perhaps the 

 reason for its existence is removed — and we get pro- 

 duced the phenomena with which the Society for 

 Psychical Research is accustomed to occupy itself, 

 regardless of mathematical theories concerning the 

 nature of proof. 



EXPOSURE OF THERMOMETERS FOR 

 THE DETERMINATION OF AIR 

 TEMPERATURE. 

 'PHE report of the Prussian Meteorological Institute 

 *■ for 19 1 1 contains the fourth communication by 

 Prof. G. Hellmann upon the above subject. The 

 observations are discussed at considerable length under 

 three principal heads : — (i) Exposure at a north window 

 (formerly the usual method adopted in Germany) and 

 in a Stevenson screen in a meadow (or field) at 

 Potsdam. This section is accompanied by an in- 

 teresting set of monthly diagrams showing the mean 

 daily range due to both exposures. (2) Comparison 

 of the Stevenson screen with the aspiration thermo- 

 meter at Potsdam and Griinberg, in Silesia. (3) Com- 

 parison of the true air temperature in a meadow and 

 in the north shade of Potsdam Observatory (about 

 half a metre from the wall). 



The following shortened summary gives some of 

 the chief results deduced from the four communica- 

 tions : — 



(1) The determination of the temperature near the 

 north wall of a building is practically independent of 

 the nature of the window exposure; the thermometer 

 may even be hung freely, so long as it is not exposed 

 to direct or indirect radiation. 



(2) An aspiration thermometer installed near the 

 north wall of a building gives results agreeing very 

 closely with those of the usual window exposure ; in 

 the summer half-year the latter gives oi°-o-2° (C.) 

 higher readings in the afternoon, while in the winter 



NO. 2275, VOL. 91] 



season the morning and evening observation hours 

 give rather too low r readings. 



(3) A freely exposed Stevenson screen gives in North 

 Germany too high readings at the afternoon observa- 

 tion throughout the year to the extent of o'i°-o'2° 

 in winter, and o'2°-o'4° in summer. At the evening 

 reading also it is o'i°-o'2° too high in summer, and 

 o'i° too low in the other seasons; at other hours the 

 differences are very small and of varying sign. 



(4) The errors of this screen differ in different 

 climates and with varying conditions of weather. 



(5) The true temperature in the shade, on the north 

 side of a building, both as regards absolute amount 

 and daily period, is quite different from that obtained 

 in an open field. At the 2h. p.m. reading the excess 

 of temperature in the field is o'i° in December and 

 i'o° in July. These differences increase with duration 

 and intensity of sunshine, and decrease with strong 

 winds. 



(6) The true daily means in the north shade of a 

 building and in a meadow differ but little from each 

 other; in winter the meadow daily mean is o'i°-o"3° 

 the lower of the two. 



(7) The hourly readings in the two positions are not 

 comparable, but the daily means derived from the 



hours 7, 2, 9 bv Kamtz's formula exhibit relatively 

 small differences. 



(8) The daily oscillation of temperature near the 

 house is about o'^° in December to i'6° in June less 

 than in the meadow. 



(q) The daily maximum is from o'i hour in Decem- 

 ber to o'q hour in June later in the shade of the house 

 than in the meadow, but the time of the occurrence of 

 the minimum is the same in both positions. 



HYDROGRAPHY IN ITALY. 1 



THE third annual report on the activities of the 

 Italian Hydrographic Department deals with the 

 year 191 1, a period which is stated to have been of 

 particular importance in its history, on account of 

 certain drastic changes which were brought about in 

 the administration of the service, through the passing 

 of a law for the better regulation of the work of col- 

 lecting and classifying data relating to rivers and 

 their mountain basins, to lagoons and to the sea, 

 and for the systematic study of all streams, their 

 sources and outlets. 



This new law assigned to the hydrographic service, 

 in addition to the director, four specialist assistants, 

 and has rendered possible the subdivision of the de- 

 partment into four sections, distinguished as fluvial- 

 hydrographical, maritime-hydrographical, meteoro- 

 logical, and geological. 



The report deals with the present and proposed 

 fields of operations, and enumerates the various sub- 

 services to be undertaken. These are as follows : — 

 (a) Meteorological ; (b) aerological ; (c) telegraphic, for 

 forecasting the weather; (d) meteorological, for the 

 city of Venice; (e) midday signalling for the port of 

 Venice; (/) pluviometric ;" (g) nivometric ; (fe) hydro- 

 metric; (i) stream measurement; (/) flood prediction; 

 (m) levelling observations; (n) maregraphic; (0) mare- 

 graphic for the city of Venice; and (*) maritime 

 lagoon reclamation. Of these services (b), (d), (e), 

 and (g) were only inaugurated in u>i2. 



Within the limits of a brief notice it is not possibli 

 to do more than thus indicate in very general terms 

 the extent of ground covered by the report, and those 

 who desire fuller information or who are interested 

 in any way in the extension and development of hydro- 



xy Gi, 



Annuale del Dii 

 Pp. yr+plates- 



dell' Ufficio Idrosr.ifico.' 

 (Venice : Carlo Ferrari, 



