PREFACE ix 
is heavy and clayey, in summer becoming hard and cracking 
into deep fissures. Its calcareous composition prevents the 
cultivation of calcifuge plants. In one part of the garden 
only a small travertine deposit forms a sandy soil. This, 
though somewhat calcareous, suits fairly well a number 
of fine-rooted plants and has lately been planted with 
Proteaceze, Melaleucas, &c. On the French side of the 
Riviera, from Antibes to beyond Cannes, quite a different 
soil prevails, the result of porphyritic and granite rocks, 
permitting the cultivation of a great many plants which 
succeed but imperfectly at La Mortola. 
The climate of La Mortola is the typical one of the 
northern Mediterranean: the summers are dry, and rain 
falls chiefly from autumn to spring. It is more copious in 
the three autumn months—October (sometimes even towards 
the end of September), November, and December, than from 
January to March. Thunderstorms, though not frequent, 
may occur at any season; they are most usual in May or 
June. But, generally speaking, the rainfall is irregular, and 
three months may pass with little or no rain, and this may 
happen not only during the summer but also in winter. 
The drought is often such that even large fleshy Opuntias 
become shrivelled and withered. No garden could exist 
under these conditions without an artificial water supply, 
and this is here provided by large tanks. 
The average annual* rainfall for ten years (1900- 
1909) has been about 851°00 mm. (over 334 inches); the 
minimum was, in 1908, only 488°70 mm., the maximum, in 
1907, 1199°20 mm. We reckon about 50 to 58 rainy days 
per annum as the average. 
The beneficial effect of the rainfall is further dimin- 
ished by the steep incline of the land. Moreover, the 
great number of cloudless days on which brilliant sunshine 
is accompanied by hot and dry winds are a_ noticeable 
feature of this climate. 
The temperature on the Riviera is not extremely high. 
The hottest days only show 31°C. (= 88°F.) in the shade ; 
nevertheless, the summer is very trying owing to the 
moist atmosphere, the continuous bright hot weather, and 
the warm nights, which only cool down towards morning in 
* The monthly average for this period shows the following figures :— 
January, 27°40 mm.; February, 75°10 mm.; March, 92°80 mm.; April, 
56°60 mm.; May, 36°30 mm.; June, 68°10 mm.; July, 2440 mm.; 
August, 35°40 mm.; September, 55°50 mm.; October, 167:90 mm. ; 
November, 117:10 mm.; December, 94°40 mm. 
