i8 



NA TURE 



[Afay 7, 1874 



all stations, if comparability is aimed at. The level of the water 

 in the dish must remain constant, for the obvious reason that the 

 evaporation is less the deeper the surface of the water stands 

 under the edge of the vessel. Provision must be made for read- 

 ing off the quantity evaporated with accuracy. The measure- 

 ment of evaporation by means of floating apparatus on large 

 surfaces of water should be introduced wherever possible. 



15. (it) The degree of cloudiness is to be given by the figures 

 o — 10, in which o represents a sky quite free from clouil, and lo 

 an entirely overcast sky. These figures refer only to the exten- 

 sion and not to the thickness of the cloud, the latter being indi- 

 cated by accompanying expressions, such as "slight," "great," 

 &c. 



(1^) Arbitrary symbols representing rain, snow, fog, &c., were 

 adopted. 



16. It was resolved that the institution of obsen-ations on 

 atmospheric electricity be recommended only for head obser- 

 vatories. As regards ozone, the exisiing methods of deter- 

 mining its amount in the atmosphere aie insufficient, and the 

 Congress therefore recommended investigations for the discovery 

 of better methods. 



17. It was agreed that for observations as well as for pub- 

 lications, the use of the same units of measure is desirable ; that 

 among all existing systems of measure the metric has the best 

 prospect of universal adoption ; that it is most desirable, if it be 

 not possible to introduce uniform measures at present, to use 

 hencelorth only metric and English measures (with Celsius and 

 Fahrenheit scales), and that all action is to be supported which 

 tends to the introduction of the uniform metric system. It was 

 also agreed that the )esults of objervation-s or the means, should 

 be published in the metric scale as well as in the original scales. 



18. The hours of observation should be chosen which give a 

 close approximation to the true mean temperature of the day. 

 The following are the suitable combinations : — 



10 4 10 ; 



vith min. 

 temp. 



S 8 

 9 9 



Observations should be set on foot at a number of normal 

 stations, especially in Turkey, East Indies, Australia, Southern 

 States, and Brazil, in order to ascertain the corrections for the 

 most important meteorological elements, such as temperature, 

 pressure, and humidity. 



19. As units of time should be chosen (l) the mean solar day 

 of the place of observation, reckoned from midnight to mid- 

 night ; (2) the civil year; (3) the civil months everywhere, the 

 calculation of the monthly means being simply arithmetical ; and 

 (4) Dove's 5-day means (73 in the year) for a selected number of 

 stations of each country. It is proposed to count the first 12 

 hours ot the day, from i to 12, as forenoon ; and the following 

 12 hours, from I to 12, as afternoon ; thus counting 12 cclock 

 midnight as the end of the day, and 12 o'clock noon as the close 

 of the forenoon. 



20. It is resolved to choose, as the periods for calculation of 

 normal values, intervals of five years to be called Lustra, so that 

 the next Lustrum will begin with January i, 1S76 ; and that as 

 regards the more important data, old observations should be 

 calculated in accordance with this proposal. 



21. The existence of a system ot weather telegraphy is, for all 

 countries, considered to be a necessity ; in addition to the direc- 

 tion and force of the wind, the barometric gradients at the time 

 of observation should also be added. For purposes of storm 

 warnings, the reduction of the barometer readings to mean sea- 

 level for places not above 1,000 feet in height is admissible. 

 For greater heights, the gradients are to be referred to the mean 

 normal heights of the barometer at the stations. The relations 

 of temperature, moisture, rain, cloud, and state of the sea and tides 

 to storms, are recommended for investigation. As regards storm 

 warnings, each director should give his opinion on the probable 

 course of atmospheric disturbances which are expected, or have 

 already commenced, not as prophecies, but as prebabilities. 

 Only wind-force of S, and upwards, of Beaufort's scale should 

 be announced. 



22. As regards maritime meteorology, it is desirable that each 

 country should, if possible, collect all its meteorological observa- 

 tions at one place, and that the Institute for Maritime Meteorology 

 should be established as near as possible to the sea, and that 

 this institute might best be placed under the general manage- 

 ment of the chief institute of the country. The convening of 



a maritime meteorological conference was declared to be desirable, 

 and the preparation for this conference is entrusted to the per- 

 manent committee appointed by the Congress. 



23. It is necessary that in every country, at least one but in 

 case of necessity several central institutions should be established 

 for the management, collection, and publication of meteorological 

 observations. 



24. The verification of all instruments supplied to meteorolo- 

 gical stations, and the inspection of stations yearly, but at least 

 once in the course of every five years, is necessary. With regard 

 to instnmiental errors detected on verification, or inspection, cor- 

 rected results only should be published. It is intended that 

 the Permanent Committee prepare, in conjunction with the other 

 members of Congress, instructions for the institution and discus- 

 sion of meteorological observations. 



25. As regards standard barometers and thermometers, each 

 central office is recommended to adopt a real standaid barometer, 

 /.(•. an instrument which allows of the determination of atmo- 

 spheric pressure according to its definition in absolute measure, 

 and to prepare a standard thermometer on scientific principles. 



26. The publication of observations at stations of the first 

 order should be entirely separated from those of stations of the 

 second order. It is handed over to the Permanent Committee 

 to prepare, in conjunction with members of Congress, a form of 

 publication suited for international purposes. 



27. It is desirable to organise, on the model of the Smithsonian 

 Institution at W-ishington and the Central Bureau at Plaarlem, 

 a similar office for the exchange of publications in every country. 



28. A Permanent Committee of seven, with the right of in- 

 creasing their number to nine, was appointed, with Dr. Buys 

 Ballot as president. The duty of this committee is to care for 

 the carrying out of the decision of the Congress, and arrange for 

 convening a future Congress ; and it shall place the delegates of 

 the Congress in cognisance with its action and proceedings. 



For the extension of meteorological knowledge it was recom- 

 mended that stations provided with self-registering instruments 

 be established on high mountain-tops ; that experiments on the 

 possibility of continuous meteorological observations with captive 

 balloons be instituted ; that stations be established in the North 

 Polar regions, and also in the high southern latitudes ; on the 

 north coast of Africa ; that the organisation of the stations in 

 Turkey be made more complete, especially the Central Observa- 

 tory at Constantinople, and that the meteorological station at 

 Athens be maintained. 



29. The establishment of an International Institution for the 

 Advancement of Meteorology was declared to be really useful 

 and desirable, and it was remitted to the Permanent Committee 

 to prepare a detailed scheme for tliis purpose for the comidera- 

 tion of a future Meteorological Congress. 



{To be continued^ 



SCIENTIFIC SERIALS 



Poggendorff'' s Aitnaltn dci- PhysiJ; und Chcmie, No. I, 1874. 

 — In this number M. Holz communicates an account of experi- 

 ments on bar-magnetism which he made in Prof. Helmholz's 

 laboratory. They had reference to the effect produced on mag- 

 netic moment of bars, when these were subjected to the corrosive 

 action of dilute muriatic acid for tv.-enty-four hours. lie finds 

 (among other tilings) that the amount of magnetic moment of a 

 steel bar, with regard to quality, depends on the structure of the 

 iron, and the carburet of iron {Karboiicisen] united with it ; that 

 it increases per unit of weight, through abstraction of magnetised 

 iron, and decreases through abstraction of magnetised carburet 

 of iron ; also, that particles of carburet of iron remaining after 

 solution of the iron are magnetisable, and receive permanent 

 magnetism. — M. Lehnebach gives a determination of the emissive 

 power of dark bodies, by the ice-calorimetric method. The 

 principle is briefly this : Suppose a thin glass sphere filled with 

 ice, and placed within a larger sphere, whose temperature is 

 above 0°, and constant ; also that the former has an arrangement 

 for showing the amount of ice melted in a given time, and a 

 vacuum can be made within the spheres ; then the increase 

 of heat received by the inner globe may be measured calori- 

 metrically. The apparatus is said to prove very serviceable for 

 measuring emissive power. — M. Braun investigates some points 

 connected with ela-tic vibrations, the ampUtudes of which are 

 not infinitely small ; and M. Meyer studies the theory of elastic 

 effects. — A method of graphic representation of absorption- 

 spectra is described by M. Vierordt, and the curves are given for 



