AN ESSAY ON SOUTHERLY BURSTERS. 177 



are for one season only, and that season an eminently unfavourable 

 one for the collection of useful data. 



The question whether bursters arrive here by preference at any 

 particular hour, and whether such hour varies from year to year, 

 as well as the average number for each hour, the percentage of 

 the whole that came at each hour seem to me best answered by a 

 diagram and 



TABLE I. 



In Table No. 1, all the bursters that have been recorded at 

 Sydney from September 30, 1863 to March 31, 1894, are grouped 

 together so that they can be seen at a glance, all the bursters that 



NUMBER IN EACH HOUR AND YEAR.* 



are on record for each year, and for each hour of the day, also 

 the total number at each hour for the whole period, and the per- 

 centage of bursters that have taken place at each hour in figures 

 and in diagram. Each stroke in the table represents a burster, 

 where several bursters have occurred at the same hour there is a 

 group of strokes, and the eye catches at once those hours in each 

 year in which bursters have been most frequent, the greatest 

 number for any hour in any year was between 9 and 10 p.m., 1891, 

 where ten were recorded. 



VARY FROM YEAR TO YEAR. 



The number for each year varies considerably, the greatest being 

 fifty-six in 1869 ; the least, sixteen, in 1890. Since 1888 there 

 has been a gradual falling off in the number, and this is coincident 

 with abundance of rain each year. 



PREFERENCE FOR A PARTICULAR HOUR. 



The Table No. 1 shows that from 11 a.m. to 1 p.m. bursters are 

 fewest, while they are most frequent from 6 p.m. to midnight, 

 the chances being slightly in favour of 7 to 8 p.m. 



* See also at foot of Diagram in., page 179. 



L-July 4,1894. 



