554 SCIENCE PROGRESS 



entering the eye are 12*5 x io -10 and 11*2 x io -10 ergs per sec, 

 approximately a mean of the results obtained by Russell and 

 Reeves. Part of the difference between the various results 

 is no doubt due to the eyes of different observers not being 

 of the same sensitiveness. 



It is interesting to note that if the limit of visibility is a 

 star of magnitude 8 m , the maximum distance at which a 

 standard candle is visible in perfectly transparent air is about 

 27 km. 



Comparative Climatology. — A valuable discussion of the 

 relative merits of different regions as regards their suitability 

 for white settlement has been made by Dr. Griffith Taylor 

 (Commonwealth Meteorological Bureau, Melbourne, Bulletin 

 No. 14). The basis of such a discussion must obviously be a 

 knowledge of the various meteorological elements at the 

 various centres, for it is primarily upon these that the health 

 and comfort of the human race depend. It is therefore neces- 

 sary to combine these elements in such a way as to obtain a 

 rapid and accurate criterion of the suitability of any centre. 

 Dr. Taylor finds that the most suitable elements to use are 

 the wet-bulb temperatures and the relative humidities. The 

 monthly means of these quantities are plotted against rectangu- 

 lar co-ordinates and a polygon formed by joining up the 

 twelve points. This figure is called a " climograph " and 

 presents a large amount of information at a glance. The 

 mean of the climographs for twelve important centres of Anglo- 

 Saxon settlement gives a standard figure, with which any 

 other climograph may be compared. Its limits are : summer, 

 (wet bulb) 62°F., humidity 68' 5 per cent. ; winter, (wet bulb) 

 37 F., humidity 81 per cent. With this figure, typical climo- 

 graphs for a large number of stations in many different regions 

 are compared. Dr. Taylor hopes that this investigation may 

 serve as " a scientific basis to the climatic aspect of Empire- 

 building," and has discussed in detail in a separate memoir 

 its application to Tropical Australia. For this memoir he has 

 been awarded the Gold Medal of the Royal Geographical 

 Society of Queensland. 



The following is a selection from amongst the most important 

 papers recently published : 



Theory of Errors. — Schlesinger, F., On the Errors in the 



