Notes and Memoranda. 319 



Canadian specimens to one of our Canadian subscribers, who signs himself 

 " J. J. B.," and dates from Napanee. We beg him to accept our thanks. He 

 compares the plumules, which he rightly designates " puffy," to a " boxing- 

 glove with two fingers or thumbs." Mr. E. C. Eye was kind enough to compare 

 this Canadian butterfly with others. He tells us that it is closely allied to the 

 American P. cruciferorum, and that both are most likely localized forms of our 

 common green-veined white. 



Star Magnitudes. — In the Transactions of the Manchester Philosophical 

 Society will be found a paper by Mr. Knott on the Comparative Magnitudes 

 assigned to Stars by Admiral Smyth in the Bedford Catalogue, by Struve in the 

 Mensurce Micro metriva, and by Argelander in the Bonner Stem-verzeichniss. " It 

 appears that the scales of the Bedford Catalogue, of the Bonner Stem-verzeich- 

 niss are practically identical down to the 9th mag., and assuming with M. Pogson 

 that the 13 mag. of Argelander's scale corresponds with the 16 mag. of Admiral 

 Smyth, we may tabulate the results below the 9th, thus : — 

 Mag. Sar. Mag. A. 



10 96 



11 101 



12 10.7 



13 11-3 



14 11-9 



15 12-4 



16 13 0" 



So far as Mr. Knott's observations go, this proportion is found to hold good. He 

 says further, " The coincidence between the scale of the Bedford Catalogue and 

 that of the Mensurce Jdicrometrica ceases practically with the naked eye mag- 

 nitudes. At the 6rh mag. the scales diverge, and the 11th mag. of the one cor- 

 responds with the 13th mag. of the other. Five magnitudes of Admiral Smyth's 

 scale, below the 11th, are represented by only one magnitude in the scale of Pro- 

 fessor Struve." 



Me. Slack's Diaphragm Eye-pims.— At the October meeting of the Micro- 

 scopical Society of London, Mr. Slack exhibited a microscopic eye-piece which he 

 had devised, and which was made by Mr. Boss for the purpose of protecting the 

 eye against the glare of a large and strongly-lit field. It has four shutters, each 

 capable of separate motion, and enables objects of any form to be exhibited in a 

 field of any dimensions required, and bounded by straight lines. This field may be 

 long or short, broad or narrow, as the object may require, and it is found that the 

 exclusion of unnecessary light makes the objects more distinct, and avoids 

 fatigue to the eye. The shutters are moved by small milled heads attached to 

 the flange of the eye-piece. A similar eye-piece will probably be found convenient 

 for astronomers when viewing the moon, or the solar disk. 



Spiders and Earwigs. — An illustration of the tact and skill, of the spider 

 in dealing with a dangerous foe, may be obtained by putting an earwig into 

 the web of the Epeira diadema, common in all gardens. On perceiving the 

 earwig, the spider advances cautiously, and when near the creature turns her 

 abdomen towards it, and shoots out a sheaf of threads which immediately adhere 

 to the earwig. She then pats him round and round as if she were roasting him 

 on a spit, and in the course of a few seconds he is effectually rolled up in a silk 

 mummy cloth, from which there is no escape. 



Soap Beans oe China. — Comptes Rendus contains a paper by M. Payen on 

 the beans of a plant belonging to the genus dialium, which are used instead of 

 soap in many provinces of China. The Chinese remove the outer skin with a 

 knife, and then rub the bean against wet linen which they wish to wash. A 

 rinsing completes the process. The pericarp, which is dry in most beans, is of a 

 fleshy character, and contains saponine, besides many other substances. M. Payen, 

 also found in these beans a gelatinous substance, differing from pectin, pectose, 

 etc., and which he calls dialose. 



Earthquake in France, September 14, 1866. — M. Bovet describes the 

 particulars of this earthquake to the French Academy. It occurred about ten 

 minutes past five, a.m., and there were two oscillations, the first from west to 

 east, the second south to north, and with an interval of a few seconds between them. 



