1869.] Mineralogy. 553 



records furnislied by their self-recording instruments in the study 

 of weather, and their publication in a graphical form, which shall 

 be acceptable to the scientific i^ublic. It is satisfactory to learn 

 that some progress is being made in placing weather study on a 

 secure scientific basis. 



Part II. of the Eeport is an account of the means adopted by 

 the Meteorological Committee, in conjunction with the Kew Com- 

 mittee, to ensure accuracy in the numerical results obtained from 

 the records of the observatories. According to the plan adopted, 

 each observatory supplies to Kew the photograms furnished by the 

 instruments, together with hourly numerical values of the readings 

 obtained by measurement. These are examined at Kew; and 

 when certified as correct, are sent to the central ofiice in London 

 for discussion, &c. 



The experience of the first few months showed that a more 

 searching examination at Kew than had at first been contem- 

 plated was necessary, in order to prevent errors creeping into so 

 large a mass of figures. The mode in which this examination is 

 carried out is given at full length. 



On the fly-leaf of the Keport we see notices of other publica- 

 tions; an account of which, together with other meteorological 

 literature, must be reserved for our next number. 



9. MINEEALOGY. 



Nothing tends more to impede the progress of a science than the 

 hasty enunciation of laws based upon too narrow an induction. 

 As our means of observation become extended, it is easy to detect 

 the fallacy of many of our premature generalizations ; but it is 

 extremely difiicult to eradicate the influence which they may have 

 exerted on the formation of our scientific ideas. Our attention has 

 recently been directed by Dr. Laspeyres to the crudeness of many 

 of those general propositions which, for several years past, have 

 been accepted, with more or less reservation, as natural laws regu- 

 lating the association of those minerals which enter into the com- 

 position of rocks. His remarks will be found in an excellent paper 

 " On the Association of Magnetic and Titaniferous Iron-ores in 

 Eruptive Eocks, and on the so-called Laws of Petrography."* It 

 is commonly laid down, as a general proposition, that the two 

 minerals here coupled together never occur associated as com- 

 ponents of a rock — that, indeed, the presence of the one inva- 



* 'Ueber das Zusammenvorkommen von Magueteisen unci Titaneisen in 

 Eruptivgesteinen, ixnd iiber die sogenannton petrographischen Gesetze.' Leon- 

 hard und Brouu's ' Jalirbuch fur Mineralogio,' u.s.w., 1869, p. 513. 



