SILLIMAN'S JOURNAL. 



185 



■which the}' have called Rhizanthea. Mr. Griffiths, 

 on the other hand, who was eminently qualilied, 

 both as a systematic and physiological botanist, to 

 judge of such a question, has adaj)ted the opposite 

 view taken by other observers, namely, that these 

 plants really belong to several distinct, and not even 

 nearly related, families ; the points of internal 

 structure and external ajipearance, which they have 

 in common, arising from the peculiar mode in which 

 they receive their nourishment. 



There is no stronger or more deeph" root- 

 ed popular belief, than that of the effect of 

 the moon upon the changes of the weather. 

 The most careful experiments have been 

 made lately, to ascertain whether there is 

 any ground for believing the moon's attrac- 

 tion to act upon the atmosphere. These 

 have resulted in establishing, beyond a 

 doubt, the existence of tides in the air, as 

 well as in the water, which surround the 

 earth. 



The doctrine of the influence of the moon and of 

 the sun on the tides was no sooner established, than 

 it became eminently probable that an influence ex- 

 erted so strongly upon a fluid so heavy as water, 

 could not but have the lighter and all but imponde- 

 rable fluid of air under its grasp. I speak not of 

 the influence attributed to the moon in the popular 

 language and belief of nations ancient and modern 

 — of Western Europe and of Central Asia, in re- 

 spect to disease ; but of the direct and measurable 

 influence of the moon and of the sun in respect to 

 the air. It is now clear, as the result of the obser- 

 vations at St. Helena by my friend Col. Sabine, that 

 as on the waters, so on the atmosphere, there is a 

 corresponding influence exerted by the same causes. 

 There are tides in the air as in tiie sea ; the extent 

 is of course determinable only by the most careful 

 observations with the most delicate instruments ; 

 since the minuteness of the effect, both in itself and 

 in comparison with the disturbances which are oc- 

 casioned in the equilibrium of the atmosphere from 

 other causes, must always present great difficulty 

 in the way of ascertaining the truth — and had, in 

 fact, till Col. Sabine's researches, prevented any 

 decisive testimony of the fact being obtained by 

 direct observation. But the hourly observations of 

 the barometer made for some years past at the Mete- 

 orological and Magnetical Observatory at St. Hele- 

 na, have now placed beyond a doubt the existence of 

 a lunar atmospheric tide. It a])pears that in each day 

 the barometer at St. Helena stands, on an average, 

 four thousandths of an inch higher at the two ])e- 

 riods when the moon is on the meridian above or 

 below the pole, than when she is .six hours distant 

 from the meridian on either side ; the progression 

 between the maximum and minimum being more- 

 over continuous and uninterrupled : — thus furnishing 

 a new element in the attainment of physical truth ; 

 and, to quote the expression of a distinguished for- 

 eigner now present, which he uttered in my own 



Vol. II. 24 



house when the subject was mentioned, " we are 

 thus making astronomical observations with the 

 barometer" — that is, we are reasoning from the po- 

 sition of the mercury in a barometer, which we can 

 touch, as to the position of the heavenly bodies 

 which, unseen by us, are induencing its visible fall 

 and rise. " It is no exaggeration to sa)'," and here 

 I use the words of my friend, the Rev. Dr. Robin- 

 son, — " that we could even, if our satellite were 

 incapable of reflecting light, have determined its 

 existence, nay. more, have approximated to its ec- 

 centricity and period." 



I am unwilling to quit this subject without ex- 

 pressing my deep sense of the services rendered to 

 science by the patient, laborious, unobtrusive obser- 

 vation and researches of my eminent friend, Col. 

 Sabine, in meteorology, and above all, magnetism, 

 in connection with diff'erent and very distant points 

 of the earth : researches undertaken, some of them, 

 before public attention was so generally called to 

 the subject as it has been in later years — (since the 

 Britisii Association urged the importance of such 

 investigation upon the government at home ;) and 

 undertaken at great sacrifice of domestic comfort, 

 and at the risk of life, not in the ordinary duties of 

 his noble profession, but in the pursuit of science 

 for its own sake — science, one year at the North 

 Pole, and the next, I think, in Sierra Leone. The 

 reputation thus acquired does not come quickly, but 

 it comes surely; and will survive permanently; and 

 the reputation of the individual adds to the reputa- 

 tion of his country. 



The following remarks on Astronomy, al- 

 luding to the greatest discovery of the age, 

 will be read with interest by all : 



I begin with Astronomy. — The progress of as- 

 tronomy during the past year has been distinguished 

 by a discovery the most remarkable, perhaps, ever 

 made as the result of pure intellect exercised be- 

 fore observation, — and determining without obser- 

 vation the existence and force of a planet ; which 

 existence and which force were subsequently veri- 

 fied by observation. It had previously been con- 

 sidered as the great trial and triumph of dynamical 

 science, to determine the disturbances caused by 

 the mutual action of " the stars in their courses," 

 even when their position and their orbits were fully 

 known ; but it has been resen'cd for these days to 

 reverse the process, and to investigate from the dis- 

 cordance actually observed, the existence and the 

 place of the wondrous stranger which has been si- 

 lently, since its creation, exerting this mysterious 

 power. It was reserved for these days to track the 

 path and to measure the force which the Creator 

 had given to this hitherto unknown orb among the 

 myriads of the air. 



I am aware that Lalande, more than fifty years 

 ago, on two nights — which, if he had pursued the 

 object then first discovered, would have been well 

 distinguished from the rest of the year, and would 

 have added new glory to his own name — did ob- 

 serve what is now fully ascertained to have been 

 the planet Nept\mc ; but though Uranus had just 

 been added to those bright orbs which to mortal 

 eves for more than two thonsand years have been 



