Notices respecting New Books. 563 



to exaggerate local irregularity (i. e. to give larger oscillations 

 about the mean than usual) ; and it is also possible that in conse- 

 quence of local, geographical, or other peculiarities, these exagge- 

 rated local irregularities may tend in certain cases to recur at the 

 same parts of the earth's surface. So far as I have been able to 

 investigate the evidence for and against the connexion between the 

 sun-spot period and rainfall and other phenomena, it has confirmed 

 this conclusion or hypothesis." 



The Report on the Madras Cyclone of May 1877 is a most 

 masterly production, entering fully as it does into the meteorology 

 of India and the Bay of Bengal during the transition-periods pre- 

 ceding and succeeding the south-west monsoon, also the meteo- 

 rology of India and the Bay of Bengal immediately antecedent to 

 the generation of the cyclone, the meteorological phenomena accom- 

 panying the formation, advance, and dissipation of the cyclone, the 

 probabilities of the occurrence of cyclones in the Bay at certain 

 seasons, including an investigation into the causes of cyclone 

 generation and motion in the Bay of Bengal. 



The following are a few of the conclusions at which the author 

 has arrived respecting cyclone generation, motion, and occurrence : — 



" Cyclonic disturbances of small intensity are of frequent oc- 

 currence during the prevalence of the south-west monsoon or rainy 

 season. Cyclones or revolving storms of great extent and intensity 

 occur only at the transition-periods, viz. at the April transition- 

 period preceding the south-west monsoon, and the October trans- 

 ition-period succeeding the south-west monsoon and ushering in 

 the north-east monsoon." 



" Cyclone occurrence is most probable during the October trans- 

 ition-period, when the most intense and extensive cyclones occur." 



" The most powerful cyclones in the Bay of Bengal tend to 

 occur at or about the minimum sun-spot period." 



"Cyclones formed at the commencement of the April trans- 

 ition-period or near the end of the October transition-period are 

 usually generated in the south of the Bay, and proceed towards 

 the Coromandel coast." 



" Cyclones generated during the latter part of the April transition- 

 period or the greater part of the October transition-period (i. e. to 

 the end of October) usually take their origin in the centre of the 

 Bay to the west or north-west of the Andamans, and advance 

 towards the coast of Ganjam, Orissa, or Bengal." 



" There is a strong antecedent probability, derived from past ex- 

 perience, of the occurrence of at least one intense cyclone at each 

 minimum sun- spot period." 



" The invariable antecedents of powerful cyclones at the two 

 transition-periods are approximate uniformity of pressure over and 

 round the coast of the Bay of Bengal, light and variable winds or 

 calms over a considerable portion of the Bay, and little or no rain- 

 fall over the coast region, as well as in the Bay : the weather is 

 hence sultry, the sea smooth ; the amount of aqueous vapour 

 accumulates and finally gives rise to peculiar sky effects. The imme- 



