416 HOLLAND SOCIETY OF SCIENCES OF HAELEM, 18G9. 



VIII. Tlio society solicits exact deterniinntions regarding the vaiiation of the 

 indices of the refraction of water, for at least L'S points of the spectrum, on an 

 extent of 50 degrees of the centigrade thermometer. 



IX. It is known that the aurora borealis gives rise to telluric electrical cur- 

 rents which sometimes introduce considerable perturbations in the service of tel- 

 egraphic lines. The society regards it as an object of interest that on tele- 

 graphic lines of great length determinations of the force of those currents should 

 be made, to the effect, among others, of ascertaining to what point they extend 

 towards the equator. 



Questions to which an answer must he returned before 1st of January^ 1873. 



I. The society desires a complete critical review of the different phanerogamic 

 floras of Europe, as well of those which have been published separately as of 

 those which are to be found in the transactions of learned societies and in scien- 

 tific journals. This review should be so arranged that the details concerning each 

 country or province shall be mentioned in succession one after the other, accord- 

 ing to the date of their publication. The work must be accompanied with crit- 

 ical observations relative to the greater or less value properly to be attributed 

 to each flora, and to the opportunity afforded of deciding on the indications 

 observed, or of proceeding to new researches in countries little known. 



II. The societ}' calls for a complete critical review of the difi'crent faunas of 

 Europe, as well of those which have been published separately as of those 

 which are extant in the collections of learned societies and in scientific journals. 

 This review should be drawn up in the same form as regards arrangement and 

 with the same conditions as those prescribed in the preceding question with 

 reference to the different floras of Europe. 



The following questions were last year submitted to competition by the society 

 wkh a view to tlieir being answered before the 1st of January, 1870 : 



I. Since the progressive decline and final suppression of the governmental 

 culture of spices in the Molucca islands, it has become highly desirable that 

 new lines of culture should be established in that fertile archipelago. The 

 society consequently asks : (1.) A description of the present social condition of 

 those islands, especially as regards the population and its aptitude for agricul- 

 tural industry. (2.) Indications of the varieties of the soil, considered in relation 

 to the culture proposed for eventual adoption. (3.) Statistical data on the results 

 of the free cultivation of spices, as it is now practiced. (4.) A statement of the 

 result of the experiment of cultivating cacao, undertaken by order of Governor- 

 general Pahud and with the effective support of the government. (5.) A detailed 

 specification of the vegetables, the culture of which would deserve to be tried 

 among those whose products are suited for exportation. 



II. It cannot be denied that spectral analysis, as at present conducted, tends 

 to fall into excess and that its value is frequently exaggerated. Consequently, 

 and in order to arrive at views at once more sound and of a more scientific char- 

 acter, it is required to make an equitable separation of the true from the false, 

 to trace the limits within which the method may be legitimately employed and 

 beyond which it ceases to be applicable, to submit to a sober critical appreci- 

 ation the facts which it has brought to light, the discoveries which it promises, 

 and those which we have a right to expect from it. 



III. The galvanic cun-ent heats the metallic conductor which it traverses ; by 

 this, the resistance of the latter is augmented, aud in this way the current reacts 



