41 8 



NATURE 



[March 3. 1892 



One piece of egg-shell dug out of the highest trench is 

 not sufficient evidence on which to base the supposition 

 that the spot was frequented as a nesting-place. 



At Glenmark, in the north of this province, the historic 

 spot where the original (somewhat larger than the 

 present) find of Dinornis reliquicc was dug out by my 

 predecessor, the late Sir Julius von Haast, the bones of 

 numerous species of birds besides moas were found. 

 Their occurrence in the situations where they were dis- 

 covered, and the way in which they were lying — entire 

 bodies with their sterna covering crop-stones in situ — have 

 been explained by the supposition that the moas were 

 overtaken by a fierce and sudden storm, and their entire 

 carcasses piled by wind and flood into vast heaps, an ex- 

 planation against which the presence here also of the 

 same powerful buzzard and other flying birds rises as an 

 objection. Yet there is nothing either in the situation or 

 the disposition of the bones to make it impossible ; still I 

 cannot help feeling that that cannot be the true explana- 

 tion which satisfies only one instance out of so many 

 assemblages of dead birds of nearly always the same 

 species in situations almost similar. I hope, however, 

 that when I have made a thorough examination of all the 

 localities where, and the conditions under which, moa 

 remains have been found, in the light of the personal 

 experience gained in the exhumation of the present de- 

 posit, and when I have completed the identification (on 

 which I am now engaged) of the smaller bird bones 

 associated in them with the moa bones, some light may 

 have been gained on this at present mysterious episode 

 in the history of the ancient Avians of New Zealand. 

 Henry O. Forbes. 



Christchurch, New Zealand, 



THE BLUE HILL METEOROLOGICAL 

 OBSERVATORY} 



'T^ HE Annals of this high class Meteorological Obser- 

 -*- vatory for 1890 are of more than usual interest, 

 since we have here presented not only the observations 

 of the year, which are made with remarkable fulness and 

 exactness, but also a well presented and discussed resume 

 by Mr. Clayton for the lustrum ending with 1890, together 

 with an account of the hourly and other observations made 

 at the Signal Service Station at Boston. The Observatory 

 is situated about ten miles south of Boston, on the summit 

 of a peaked hill 640 feet above the sea, and as the ground 

 falls down from the buildings in every direction for 

 several hundred feet, the Observatory occupies a unique 

 position among Observatories in the investigation of some 

 of the more important phenomena of meteorology. 



The hourly means of atmospheric pressure show for all 

 the months the double tide well marked. The chief 

 maximum steadily recedes from 10 a.m. in winter to 8 a.m. 

 in summer, and the chief minimum advances from 2 p.m. 

 in winter to 5 p.m. in June. The evening maximum 

 shows a slight tendency towards displacement in the same I 

 direction as the afternoon minimum, and the night 

 minimum a similar displacement in the same direction as 

 the morning maximum. A third barometric maximum, 

 which is generally met with in middle latitudes, is par- 

 ticularly well marked at this place. 



But the important position of this Observatory appears 

 in the most striking manner on comparing the hourly 

 barometric results of 1890 from the Blue Hill with those 

 from Boston for the same year. The Blue Hill Observa- 

 tory is situated on a true peak, but the station at Boston 

 is in the mouth of the rather broadish valley which 

 stretches northward from the town. The result is that 



' "Annals of the Astronomical Observatory of Harvard College," vol. xxx., 

 Part 2, '• Observations made at the Blue Hill Meteorological Observatory) 

 Mass., U.S., in the Year 1890, under the direction of A. Lawrence Rotch, 

 Esq." With Appendices. (Cambridge : University Press 1891.) 



though the places are only about ten miles apart, the 

 diurnal fluctuation at Boston is o"oi7 inch greater than on 

 the top of Blue Hill. In June, when this feature of the 

 pressure is at the annual maximum, the following are the 

 hourly results, where the plus sign indicates that pressure 

 at Boston rose above its daily average by these amounts, 

 expressed in thousandths of an inch, greater than did 

 pressure on the Blue Hill above its daily average ; and 

 the minus sign that it fell lower by these amounts at the 

 former than at the latter place. 



NO. I 166, VOL. 45] 



The explanation is that, during the night, cold air- 

 currents flow down the sides of a valley and accumulate 

 below, and thus a higher pressure is maintained in valleys 

 during the night ; but, on the other hand, during the day 

 the valleys become more highly heated by the sun, and 

 under the strong ascending currents thereby generated, 

 pressure falls lower than in open situations. The amounts 

 increase in proportion to the daily range of temperature, 

 and as the mean velocity of the wind diminishes. This 

 diurnal variation is greatest in the deep valleys of Switzer- 

 land and other mountainous regions, and, though small 

 in amount is a well-defined and steady fluctuation 

 in the valley of the Thames, as shown by a com- 

 parison of the Kew and Greenwich barometers. A weak 

 point in the meteorological publications of the Signal 

 Service of the United States is the all but complete 

 absence of the results of the hourly phenomena of 

 meteorology. In filling up this hiatus, the Blue Hill 

 Observatory will prove of the greatest service, as offering 

 a truly normal Observatory, at which, from its mere 

 position, several disturbing elements affecting diurnal 

 phenomena are eliminated. 



During the whole year, the time of occurrence of the 

 minimum temperature is very near sunrise ; and it is 

 interesting to note that the maximum occurs at all 

 seasons from 2 to 3 p.m., approaching in this respect 

 the time of the maximum at truly high-level Observa- 

 tories, or at Observatories situated on peaks. For the 

 five years, the mean monthly temperatures deduced from 

 the maximum and minimum thermometers exceed those 

 deduced from the hourly values every month, the smallest 

 excess being 0^2 in December, and the largest 1^2 in 

 August, the mean for the year being o'7. 



The prevailing winds are north-westerly from February 

 to April, southerly in May, and westerly and north- 

 westerly for the other months. These winds are ruled 

 by the different distributions of atmospheric pressure 

 over the Atlantic and America in the respective months ; 

 these being in winter the low pressure round Iceland, and 

 the high pressure over the United States and Canada ; 

 and in summer the high pressure in mid- Atlantic, together 

 with the low pressure over the Middle States. The hourly 

 frequency of each wind has been worked out for the lustral 

 period, with results that are very suggestive. The period 

 is sufficiently extended to give fairly good averages, from 

 which accidental phenomena may be regarded as elimi- 

 nated ; and the result is more completely attained by 

 the height of the Observatory above the surrounding 

 country all round removing from the observations the 

 more purely local causes of disturbance. The mean 

 hourly frequency of each wind shows a clear tendency of 

 the wind to veer around the compass each day. Thus, 

 the greatest frequency of southerly winds occurs at 8 p.m., 

 south-westerly at 10 p.m., westerly at i a.m., northerly at 



