SCIENCE. 



151 



would be sufficient to enable one to see a molecule of al- 

 bumen, or if its power could be increased one hundred 

 and seven times it would enable one to see a molecule of 

 alum. 



Now Helmholtz has pointed out the probability that inter- 

 ference will limit the visibility of small objects ; but sup- 

 pose that there should be no difficulty from that source, 

 there are two other conditions which will absolutely 

 prevent us from ever seeing the molecule. 



1st. Their motions. A free gaseous molecule of hydrogen 

 at the temperature of 0°C, and a pressure of 760 mm. 

 mercury, has a free path about tttooit mm - m length, its 

 velocity in this free path being i860 m. per second or more 

 than a mile, while its direction of movement is changed 

 millions of times per second. Inasmuch as only a glimpse of 

 an object moving no faster than one millimeter per second 

 can be had, for the movements are magnified as well as the 

 object itself, it will be at once seen that a free gaseous 

 molecule can never be seen, not even glimpsed. But sup- 

 pose such a molecule could be caught and held in the field 

 so it should have no free path. It still has a vibratory 

 motion which constitutes its temperature. The vibratory 

 movement is measured by the number of undulations it sets 

 up in the ether per second, and will average five thousand 

 millions of millions, a motion which would make the space 

 occupied by the molecule visibly transparent, that is it 

 could not be seen. This is true for liquids and solids. 

 Mr. D.N. Hodges finds the path of a molecule of water at 

 its surface to be .0000024 mm., and though it is still much 

 less in a solid it must still be much too great for observation. 



2d. They are transparent. The rays of the sun stream 

 through the atmosphere, and the latter is not perceptibly 

 heated by them as it would be if absorption took place in 

 it. The air is heated by conduction, contact with the 

 earth, which has absorbed and transformed the energy of 

 the rays. When selective absorption takes place the num- 

 ber of rays absorbed is small when compared with the 

 whole number presented, so that practically the separate 

 molecules would be too transparent to be seen, though 

 their magnitude and motions were not absolute hindrances. 



ON THE AURORA AND ZODIACAL LIGHT OF 

 MAY 2, 1877. 

 By Henry C. Lewis. 

 A simultaneous appearance of an aurora and the zodi- 

 acal light appeared on this evening, and a comparison be- 

 tween them is here given. The various changes of the au- 

 rora are given in detail. A remarkable feature was the 

 formation of a bright streamer which maintained its posi- 

 tion relative to the earth for nearly an hour. Meanwhile, 

 the Zodiacal Cone, which was bright early in the evening 

 had moved past the streamer and passed below the hori- 

 zon. The streamer had remained, like the great pointer 

 fixed to the earth, and marking its motion, while the 

 heavens revolved past it. This fact was conclusive evi- 

 dence of the terrestrial character of the aurora and of the 

 cosmical character of the zodiacal light. Another fact 

 leading to the same conclusion was the character of their 

 spectra. That of the zodiacal light was continuous, and 

 that of the aurora was a line-spectrum — the former is such 

 as would be given by sunlight reflected from matter in 

 space; the latter would he given by an electric discharge 

 through a gas. 



OBSERVATIONS ON BRACHIOPODS. 



By Prof. Edw. S. Morse. 



Mr. Morse gave the anatomical details of some Brachio- 

 pods he had studied in Japan, and described the existence 

 of a curious parasitic worm in a large species of Lingula. 

 He also gave further facts regarding the so-called hearts of 

 certain brachiopods, and expressed his belief that they were 

 glands of some kind connected with the reproductive 

 organs. 



THE KAMES OR ESKARS OF MAINE. 

 By Geo. H. Stone, Kent's Hill, Me. 



This paper is accompanied by a map showing the courses 

 of the larger Kame-systems of Maine. Omitting short, 

 isolated ridges of gravel, the map shows thirty distinct 

 systems of Kame gravels, varying from five to one hundred 

 and fifty miles in length. The total length of Karnes and 

 Kame-plains thus far mapped is about 2000 miles. The 

 map is the result of amateur explorations made at intervals 

 during the past four years. 



The paper discusses the following points regarding the 

 Karnes : 



1 . Kame drift compared with glacial drift. 



The facts show that Kame material has in general been 

 transported farther than the morainal material which was 

 originally derived from the same locality. 



2. The Kame streams. 

 The Karnes were deposited by currents flowing length- 

 wise of their courses, and in all but four undecided cases 

 the currents flowed southwards. The Kame streams re- 

 sembled sub-serial rivers in their meanderings, their 

 branches, and in all other respects. All the long systems 

 in the State are much higher at their northern than at their 

 southern ends. The water of these rivers is shown to have 

 flowed faster on long down slopes than on up slopes. 

 There is strong reason to believe that most of the water of 

 the melting glacier escaped by superficial channels, unless 

 near the terminal moraine. Except near the coast there 

 are in Maine almost no signs of sub-glacial streams. 



3, The external forms of Karnes. 

 1. The single ridge. 2. Reticulated plains, composed of 

 a series of reticulated ridges with enclosed funnels or 

 lakelets. 3. The solid or continuous plains, which are 

 broad, flat-topped ridges, showing few or no signs of separ- 

 ate ridges, and often of great height. 



4. The internal sti ucture of Karnes. 



Karnes are of two kinds — 1. The stratified Kame, which 

 is the more common type. 2. The pell-mell Kame. 



The same Kame may be stratified in one part of its 

 course and pell-mell in another. 



5. Action of the sea upon the Karnes. 

 During the Champlain period the sea stood at a height, 

 in the central parts of Maine, about 300 or 350 feet above 

 the present sea level. The Karnes are plainly overlain by 

 the marine clays, and the sea greatly modified their form. 

 The difference between the Kame that has been under the 

 sea and that which has not is often very great, and conclu- 

 sively proves that the Karnes proper cannot have been a 

 marine deposit. 



6. Topographical relations of the Karnes. 

 No general law of relationship between the Karnes and 

 the relief forms of the land can be derived from local ob- 

 servations, for there are many purely local relationships. 

 The only invariable rule thus far established is that the 

 Karnes never cross hills more than about 200 feet higher 

 than the country lying to the northward. Maine is trav- 

 ersed by numerous ranges of hills trending eastward or 

 northeastward, and the Kame systems never cross the high 

 ranges except by low passes. Low hills they cross freely. 

 The inference of the writer is that the Karnes were depos- 

 ited when the glacier was so far melted that the higher hills 

 rose above the ice surface, and hence the only escape for 

 the waters southward was by the low passes. 



7. Distribution of the Karnes. 

 A line joining the northern extremities of the Karnes is 

 nearly a straight line ; it trends nearly northeast and is 

 roughly parallel with the coast. North and west of this 

 line there are occasional short ridges of Kame origin, but 

 no long systems have yet been discovered. 



(The publication of papers read before the recent 

 meetings of the American Association for the Advance- 

 ment of Science will be continued in our next number. — 

 Ed.) 



