WHAT ARE CLOUDS? 751 



knowledge is set there, or the instinct for conduct. If the instinct for 

 beauty is served by Greek literature as it is served by no other litera- 

 ture, we may trust to the instinct of self-preservation in humanity for 

 keeping Greek as part of our culture. We may trust to it for even 

 making this study more prevalent than it is now. As I said of humane 

 letters in general, Greek will come to be studied more rationally than 

 at present ; but it will be increasingly studied as men increasingly feel 

 the need in them for beauty, and how powerfully Greek art and Greek 

 literature can serve this need. Women will again study Greek, as 

 Lady Jane Grey did ; perhaps in that chain of forts, with which the 

 fair host of the Amazons is engirdling this university, they are study- 

 ing it already. Defuit una mihi symmetria prisca, said Leonardo da 

 Yinci ; and he was an Italian. What must an Englishman feel as to 

 his deficiencies in this respect, as the sense for beauty, whereof sym- 

 metry is an essential element, awakens and strengthens within him ! 

 what will not one day be his respect and desire for Greece and its 

 symmetria prisca, when the scales drop from his eyes as he walks the 

 London streets, and he sees such a lesson in meanness as the Strand, 

 for instance, in its true deformity ! But here I have entered Mr. Rus- 

 kin's province, and I am well content to leave not only our street 

 architecture, but also letters and Greek, under the care of so distin- 

 guished a guardian. Nineteenth Century. 



-< 



WHAT ARE CLOUDS? 



By C. MOEFIT. 



THOUGH the clouds are such familiar objects, very little is known 

 about them, and the processes by which they are formed and give 

 back their moisture to the earth are unsolved mysteries. 



They can not be classified as belonging to the solid, fluid, or gaseous 

 form of matter. Yet they are defined as being " a collection of watery 

 particles in the state of vapor, suspended in the air." If they are ordi- 

 nary vapor, they must be governed by the laws which affect vapors. 

 Brande defines vapor thus : " When liquids and certain solids are 

 heated, they become converted into elastic fluids or vapors, which 

 differ from gases in this respect, that they are not under common cir- 

 cumstances permanently elastic, but resume the liquid or solid form 

 when cooled down to ordinary temperature."' According to this defi- 

 nition, clouds can not be composed of ordinary vapor, for under all 

 conditions their temperature must be below the condensing point of 

 water-vapor. 



At the elevations at which clouds are often seen, they are in the 

 regions of perpetual congelation ; and as they float above the highest 



