18 BULLETIN 186, UNITED STATES NATIONAL MUSEUM 



angestellten nieteorologischen Beobachtungen" published in Petermann's Geo- 

 graphische Mitteilung, 1909, No. 6. Dr. Hosseus gives an extract relating to Doi 

 Sutep from this paper in his book, "Durch Konig Tschulalongkorns Reich." The 

 following is a summary of this extract. 



Temperatures were taken simultaneously in Chiengmai and on the top of Doi 

 Sutep from 2 P. M. on December 10th, till 7 A. M. on December 14th. When 

 these temperatures are tabulated it is seen the mean decrease in temperature 

 between Chiengmai and the top of Doi Sutep for the four clays is at 7 A. M. 2.45° 

 C (4.4° F), at 2 P. M. 13.3° C (23.90° F) and at 9 P. M. 6.2° C (11.2° F). This 

 gives a mean fall for each 100 metres altitude of 0.533° C, which accords with the 

 value for decrease of temperature with height found in mountains elsewhere, 

 namely 0.56° C for every 100 metres (about 1° F to 300 feet). The difference in 

 temperature at night is not so great owing to the heavy cold collecting in the 

 valley. 



Taking it for granted that December is the coolest month in Chiengmai and 

 April the hottest it may be assumed that the mean temperature on the top of 

 Doi Sutep for December will be 12.2° C (54° F) and for April 22.3° C (72.1° F). 

 May, which falls in the rains when the decrease of temperature with height is 

 less, will have the same mean temperature as April. 



Combining all the results it may be predicted that the Winter months on the 

 top of Doi Sutep will have a temperature resembling that of our [German] 

 Spring months, though night frosts are hardly to be expected. The hottest 

 months, April and May, on the other hand will have a mean temperature which 

 we rarely reach in the [German] Summer months. 



Since the above paper was written a good many temperature records have 

 been made on the top of Doi Sutep and these bear out, in the main, the predic- 

 tions of Dr. Gerbing. It may be mentioned here that night frosts are not un- 

 known in N. Siam, and at lower altitudes than the top of Doi Sutep. I myself 

 experienced a frost one night in a small valley on the Baw Sali plateau in Jan- 

 uary 1904, the altitude being about 3,000 feet. I believe these frosts occur in 

 valleys at fairly high altitudes and sufficiently enclosed to act as pockets for cold 

 air. Such a valley, however, is not to be found on Doi Sutep, whose slopes are 

 steep, so night frosts there are improbable. 



Rain may fall in any month of the year in our provinces, but when 

 it does so outside the limits of the rainy season it usually falls 

 only as showers, though occasionally in the dry season there may 

 be two or three days of continuous rain. Kerr's observations from 

 1909 to 1915 gave the mean annual rainfall at Chiang Mai as 42.629 

 inches; official measurements there from 1927 to 1929 gave 43.358 

 inches; on the other hand, the Meteorological Bureau recorded there 

 only 17.350 inches in 1931 and 36.920 inches in 1932. 



BREEDING SEASONS 



It is probable that there is no time of the year when some species 

 of bird is not breeding within our provinces ; it may be added, how- 

 ever, that I have no record for any species' breeding in the month 

 of October, and only the barn owl has been found breeding in Novem- 

 ber; this latter month therefore may perhaps be considered the first 

 of the annual cycle. The number of forms known to be breeding 

 increases thereafter month by month, reaches a high point in April 



