240 THE PARKS AND GARDENS OF PARIS. [Chap. XV. 



149. Soaforthia clegans 137. Chamrerops Mnrtinna 0^^. riiconix farinifcra 



134. Uralica dulcis 119. riiochix sylvostris lOii. ChanuTrops liumilis 



13G. Pcnforthia gracilis 105. Cocos uu.stralis 102. Bralua iiitida. 



142. Chamajdoreaglaucifolia 



Hero, then, are twenty-six kinds of Palms, of varied stature, 

 and perfectly suited to form a background of foliage of supreme 

 elegance. We speak of such only as have been proved to succeed ; 

 and if the altitudes at which they grow spontaneously are com- 

 pared, it will be seen that a conservatory with a minimum of 

 38'' Fahr. is all that they require. It is known that for every six 

 hundred feet of altitude above the sea, the mean temperature 

 decreases one degree. But if we take, as is generally done, the 

 mean temperature of the tropics as 80^ at the sea-level, at 0,000 

 feet it would be only 65'^, and at 10,000 feet, 50'^, which is equal to 

 the mean temperature of Southern England. It is not, therefore, 

 very extraordinary that the Palms of these high regions, the 

 Chamaerops excelsa, for instance, can live out-of-doors in those 

 climates where they have nothing to fear but exceptional winters. 

 If we have not certain data as to this mode of culture, it is 

 because Palm-trees have hitherto been too costly to risk their 

 sacrifice in the open air. The Cycads, although generally less 

 hardy than the Palms above named, are still available for the 

 conservatory, where a low temperature for a short time would 

 not be prejudicial, though they would suffer by prolongation of 

 that temperature. Thus we would advise the following specimens 

 to be planted : — 



85. BowcTiia spcctabilis 109. Eiiccplialartos Alten- 134. Dion cdule 

 96. Cycas ruvoluta steini 120. Zaniia australis. 



Among the Tree-ferns, the following are suitable for the cool 

 winter-garden : — 



124. Alsophila australis 116. Alsophila ornata 170. Cyathca dcalhata 



82. BlecliDum brasiliense 140. Balantium antarcti- 151. Todca australis 



With plenty of space one might add :■ — 



Alsophila excelsa C. spectabilo Lomaria rycadilolia 



Balantium Culcita Cyathca medullaris Ij. gil)l)a 



B. Sellowianum C. Smitliii L. discolor 



Blechnum rio-grandcnsc Dicksonia fibrosa L. mngellanica. 

 ("ibijtium regale D. squarni.sa 



