December io, 1908] 



NATURE 



'75 



to the bottom. The other end of this siphon is passed 

 into a vessel filled with water, also reaching nearly to 

 the bottom, so that water may the more easily flow out. 

 a is the globe, 6 the siphon, and g the vessel. I assert, 

 when the globe is placed in the sun and becomes warm 

 some of the air enclosed in the tube will pass out. This 

 will be seen, since the air flows out of the tube into the 

 water, setting it in motion and producing air-bubbles, one 

 after the other. If the globe is placed in the shadow or 

 any other place where the sun does not penetrate, then 

 the water will rise through the tube flowing into the 

 globe. If the globe is again placed in the sun the water 



will return to the vessel, and vice versA The same 



effect is produced if one heats the globe with fire or pours 

 hot water over it. . . ." 



Somewhat more complicated is the similar apparatus of 

 Hero, to which he gives the name Aiflot, or drip (Fig. 3). 



Now it happened that this book of Hero on pneumatics, 

 which must have been widely distributed already in MS., 

 was translated in the eighteen years between 1575 and 

 1592 no less than twice into Latin and three times into 

 Italian. It was studied by Galileo, Porta, and Drebbel, 

 and gave, about the year 1600, to all three men the idea 

 of constructing a thermoscope, and to the last one also 

 the impulse of making an experiment on the origin of 

 "i" winds. From this it appears there is an interp^ling 



veil 



connection between the science of two remote periods with 

 an interval of time of more than 1800 years ! 



As I said before, the Greeks were also the first to start 

 theories of meteorological phenomena. Indeed, since the 

 time of the oldest philosophical school, that of Ionia, 

 there are few Greek philosophers who were not interested 

 in some branch of meteorology. This covered a wider 

 field of research then than at present, embracing, besides 

 meteorology in the modern sense, also a goo3 deal of 

 physical geography and astronomy, especially shooting- 

 stars, meteors, and comets. The favourite meteorological 

 subjects of speculation and research seem to have been 

 the origin of the winds, the theory of the rain, including 

 the regular inundation of the Nile, and the rainbow. A 

 good many cosmological speculations were also put for- 

 ward by the meteorologists which often proved false, and, 

 considered from a practical point of view, in all cases 

 rather useless, whence in the period of Socrates meteor- 

 ology itself came into disrepute. 



But notwithstanding, meteorology made some real pro- 

 gress in time, and reached such perfection a century later 

 that the system established by Aristotle remained for nearly 

 two thousand years the standard text-book of our science. 

 To be sure, considered from a modern point of view, 

 Aristotle's meteorology was antiquated long ago, but if 

 you imagine yourselves back in those old times you will 

 agree with me that his treatise of meteorology — the earliest 



xo. 2041. vol.. 70] 



one existing — is an excellent piece of worl<, and 

 worthy of the greatest systematiser of all times. 



I should go too far if I were to analyse here the merits 

 and demerits of Aristotle's meteorology. It may be 

 sufticient to say that his most distinguished successors, 

 such as Theophrastus and Posidonius, have added but 

 little to the perfection of his system, which, on the con- 

 trary, gave rise to innumerable commentaries and para- 

 phrases. All text-books of meteorology issued on the 

 Continent until the end of the seventeenth century are 

 exclusively based on Aristotle, whereas, curiously enough, 

 in England his influence was much less. If I except Duns 

 Scotus, I do not know any British scholar who has written 

 a commentary on the meteorology of Aristotle, and even 

 this one has quite recently been disputed. It is true the 

 number of treatises on meteorology published in Great 

 Britain before 1700 is unusually small compared with that 

 issued contemporaneously in Germany, Italy, and France, 

 in Latin or the vernacular language. Englishmen seem 

 always to have been more inclined to make actual observa- 

 tions of the weather than to theorise upon it and to write 

 systematic treatises on meteorology. 



' Among the Romans meteorology made but little pro- 

 gress, like all other sciences of no immediate practical 

 value. Pliny, Seneca, and Lucretius do not add any re- 

 markable fact or theory to the knowledge of the Greeks, 

 and probably the same can be said of the lost writings 

 of Nigidius Figulus and Suetonius Tranquillus. ^ From 

 Virgil we learn some new weather-proverbs originating 

 in Italy, and a writer on agriculture. Columella, who 

 owned a large estate near Cadiz in Andalusia, has left 

 behind a " Calendarium Rusticum," or rural calendar, 

 with many interesting weather observations made in that 

 district. 



The extensive colonial possessions of the Romans were, 

 of course, suitable for advancing the conceptions of 

 climatological differences of the countries. As the great 

 military expedition of Alexander the Great to inner Asia 

 and India had brought to the Greeks the first knowledge 

 of the monsoon winds, so the Romans were the first to 

 point out the difference between the continental and mari- 

 time climate. Minucius Felix, a Christian writer from 

 Africa, living in the second century .a.d., says, concern- 

 ing the climate of Great Britain, " Britannia sole deficitur, 

 sed circumfluentis maris tepore recreatur," that is, freely 

 translated, " Britain has little sunshine, but a mild climate 

 on account of the warm sea-water flowing round it." 



The barbarous state of Europe after the fall of the 

 Western Empire was not adapted to the furthering of 

 science, which was barely kept alive within the Christian 

 Church. Yet the pursuit of meteorology never wholly 

 ceased, for the Fathers of the Church, writing commen- 

 taries on the work of the seven days, the so-called 

 Hexaemeron, often took occasion, when dealing with the 

 first day of the Mosaic Creation, to insert long elaborations 

 on the atmosphere and its phenomena. 



At the very beginning of the Middle Ages the great 

 encvclopa;dists, such as Isidorus Hispalensis in Spain, the 

 Venerable Be_de in Groat Britain, and Rabanus Maurus 

 in Germany, were the first to devote more attention to 

 meteorological questions, the interest in which must have 

 been considerable in England, for in the tenth century an 

 extract of Bede's writings, concerning astronomy and 

 meteorology, was made for the uninitiated in the Anglo- 

 Saxon language, which is perhaps the earliest treatise on 

 science written in a popular form. It contains chapters 

 on the winds, rain, hail, snow, and thunder. 



A general revival of studies took place at the end of the 

 twelfth century, when the writings of Aristotle, among 

 which was his "Meteorology," came to the knowledge 

 of the Western students by Latin translations made in 

 Spain from the .Arabian ones, not from the Greek originals. 

 The imposing meteorological system of the great Stagirite 

 again exercised a great influence on the writings of the 

 scholars and on the teaching in the recently established 

 universities, where, under the title " Meteora," regular 

 courses and even exercises in meteorology were held. 

 Albertus Magnus at Cologne wrote at this time his great 

 meteorological works (" De Mcteoris." libri iv., and " De 

 Passionibus Aeris "), paraphrasing chiefly those of Aris- 

 totle, but adding also the opinions of other authorities 



