38 J. noPKiNsox — OS the obseevatiox 



necessary or interesting." In obserring any fact connected \dth 

 birds, the most important point insisted upon is that the observer 

 " should set down the exact locality at which it occurred, even 

 if it be but a few miles distance from his oy^a station, and if 

 possible again record the fact when it recurs there, or vice versa." 

 There are many valuable suggestions, in addition to the above, 

 in the excellent code of Instmctions to wliicli reference has so 

 frequently been made. 



C.AXENDAE OF PHENOMENA TO BE OBSERVED. 



The accompanying Calendar may be found useful as indicating 

 the phenomena which should be observed in the species enumerated, 

 and the probable dates of their occurrence. It is compiled from 

 the record of ten years' obsei*vations at Marlborough, given in the 

 ' Instructions ' of the Meteorological Society, and of twelve years' 

 (1820-1831) at Swaffham Bulbeck, near Cambiidge, fi'om the Ilev. 

 L. Jenyns' ' Observations in Natural Histoiy.' 



This double record may be instructive as showing the difference 

 between two localities, one of which is about the same distance to 

 the south-west of Watford as the other is to the north-east ; but in 

 comparing them it should be borne in mind that the Cambridge 

 calendar is of a period forty years before that of the Marlborough 

 calendar. It may also be mentioned that the former is not 

 uniformly a continuous record, some of the phenomena having 

 been only occasionally observed during the twelve years, while 

 others have been observed eveiy year during that period. The 

 number of years each obsei-vation was made is given in the original 

 calendar, which is prefaced by some very valuable remarks on the 

 subject of this inquiiy. 



It may be noticed that the order adopted in our calendar is not 

 exactly in accordance with the mean dates of cither the jMarl- 

 borough or the Cambindge calendar. In com]nling it, both these 

 records have been taken into consideration, and in some cases the 

 calendars of White and Markwick have also been consulted. Ex- 

 tended observation may possibly clear up such discrepancies as are 

 shown (taking two of the earlier occurrences as examples) in the 

 recorded times of flowering of the hazel and the ivy-leaved speed- 

 well, of which the mean date of coming into flower is about the 

 same at Marlborough, and yet differs by six weeks at Cambridge. 

 Although a greater in-ogularity than is even here shown m-ai/ be 

 introduced by observations in this neighbourhood, there are doubt- 

 less various causes, afl'ecting diff'erent species in different ways, to 

 the discoveiy of which these apparent discrepancies may eventually 

 lead. 



