MISCELLANY. 



2 53 



tions have been selected for observation, 

 at four of which the entrance and exit 

 of the planet will be visible, while at 

 the other five but one of the two inci- 

 dents can be observed. French savants are 

 now corresponding with the astronomers of 

 England, Germany, Russia, and this coun- 

 try, with a view to parcelling out the sta- 

 tions to the different observers in such a 

 way that all shall be favorably located, and 

 all the useful points of the earth's surface 

 available for these important observations 

 occupied. After use in 1874, the French 

 apparatus will be carefully preserved for 

 observing the transit of 1882, which is fol- 

 lowed by a period of one hundred and 

 twenty years, in which no transit occurs. 



The Boring-Organ of Pholadcs. It is 



well known that certain molluscous ani- 

 mals have the power of boring their way 

 into solid substances, making the hole thus 

 excavated their future home. The teredo 

 or ship-worm, for example, honeycombs the 

 densest timber, others excavate in clay or 

 chalk, and pholas perforates the hardest 

 rocks. With what part of the animal the 

 work is accomplished has long been a mat- 

 ter of dispute, some zoologists regarding 

 the rough, rasp-like shell as the perforating 

 organ, while others believe that the work 

 is done by the foot. In a paper on the 

 subject, read at the recent meeting of the 

 British Association, Mr. John Robertson 

 adopts, the former view, maintaining that 

 the perforations are made by the rotating 

 movements which the creature is capable 

 of imparting to its shell. In the discussion 

 which followed, Mr. Bryson, a close observ- 

 er of the habits of pholas, was quoted to 

 the effect that the boring is accomplished 

 by the foot, which, charged with siliceous 

 particles, acts like the leaden wheel of the 

 lapidary. Mr. Gwynn Jeffreys also regards 

 the foot, in all the boring Conchifera, as 

 the instrument of perforation. Several facts 

 were cited in support of this. In Teredo 

 navalis, as was long ago shown by Sellius, 

 the foot is the only organ of perforation, 

 and the posterior extremity of the shell has 

 a large excavation into which this organ 

 is received. Pholadidea in the young state 

 excavates by means of the foot, but after- 

 ward the aperture becomes closed by ge- 



latinous matter, when no further excavation 

 takes place. In pholas, also, no part of the 

 shell can act at the bottom of the excava- 

 tion, the foot alone being capable of use in 

 that position. 



The Polaris Expedition. Captain C. F. 



Hall writes, under date August 24,18*71, from 

 Tossak, North Greenland, that all goes well 

 with his vessel, the Polaris. The captain 

 has abundant supplies, and is well provided 

 with Esquimaux dogs, reindeer-furs, seal- 

 skins, etc. Hans Christian, well known to 

 readers of Kane's narrative, accompanies the 

 Polaris Expedition, together with his family 

 of wife and three children. Various charts 

 and notes of Baron von Otter, commander 

 of the Swedish Expedition, and of other 

 scientific men, are in the possession of Cap- 

 tain Hall, and have led him to abandon the 

 Jones Sound route ; to cross Melville Bay 

 to Cape Dudley Diggs ; and thence make 

 for Smith's Sound, with a view to reach 

 Kennedy Channel. 



Disastrous Volcanic Eruption. A very 

 violent eruption of the volcano of Merapi, 

 in Java, took place on the 15th of April. 

 The event was totally unexpected, and the 

 loss of life and property was great, many 

 villages being destroyed. In some places 

 the ashes fell for three days, and it became 

 so dark that lamps had to be lit. About 

 200 dead bodies had at last accounts been 

 found on one side of the volcano. 



f h finical Products of Encalyptns. Euca- 

 lyptus is the name of a genus of trees con- 

 taining many species, mostly natives of Aus- 

 tralia, where the tree is very abundant. Sev- 

 eral species yield a copious resinous secre- 

 tion, and are therefore known as gum trees. 

 Some of these attain a great size, it is said, 

 exceeding in height the giant red-woods of 

 California. The bodies are slender and with- 

 out branches, except near the top, where the 

 branchlets droop like those of the weeping- 

 willow. The leaves are entire, of a leathery 

 texture, and, instead of being placed with 

 one surface toward the ground and another 

 toward the sky, hang with their edges in 

 these positions, so that the two surfaces of 

 the leaf are equally exposed to the light. 

 The trees are of very rapid growth, and fur- 



