Notes and Memoranda. 401 



Adhesive Strength of Glue. — The tensile strength of the 

 iron exhibited has been already noticed ; one of the makers of glue 

 shows a wooden bar having the same sectional area of one square 

 inch ; when sawn across and united by glue, the joint resisted a 

 tensile strain of 504 lbs. before breaking, a remarkable contrast to 

 the 50 tons supported by the iron. 



NOTES AND MEMORANDA. 



The Companion or Sibius. — It appears that Dr. Peters has reconsidered 

 this subject, and written to Cosmos to the effect that the newly-discovered star may- 

 be that body whose existence was first conjectured by Bessel. Mr. Bond has pub- 

 lished in Sillimarts Journal some additional particulars, and he states that Mr. 

 ^afford having concluded his calculations, agrees with Dr. Peters in assigning fifty 

 years as the period of the revolution of Sirius. M. Chacornac estimates the light 

 of the companion star at one ten thousandth of that emitted by Sirius, and M. 

 Le Yerrier calculates its bulk at a tliird or a fourth of that of the larger orb. 



New Polaeiscope Object. — Mr. Marston of Ludlow recommends a double 

 oxalate of chromium and potash. He dissolves in hot water one part bichromate 

 of potash, two binoxalate of potash, and two oxalic acid. A specimen he has 

 been kind enough to forward to us exhibits splendid effects, which are improved 

 by the selenite stage. He recommends viewing the crystals with a half-inch. We 

 succeeded well with a two-thirds. 



Me. Hind's JNebexa Pound. — Messrs. Winnecke and Otto Struve saw this 

 curious variable body through the great instrument at Pultowa on the 22nd of 

 March. Its brilliancy is now little inferior to that of the comet of 1861, which 

 remains visible. On the 29th of last December the nebula was likewise seen at 

 Pultowa. 



Insect DeSteoyee. — A weak solution of chloride of lime is said to preserve 

 plants from insects if sprinkled over them. Flies are also got rid of in stables 

 and other places by scattering chloride of lime on a plank. If the same sub- 

 stance is mixed with half its weight of some fatty matter, and a narrow band of the 

 composition smeared round a tree, insects will not pass it. 



The Silkwoem Disease. — The Archives des Sciences gives an account of an 

 important discovery of the nature of this obscure and mischievous complaint, 

 which, without changing the external appearance of the silkworms, destroys their 

 value by attacking their internal organization, and especially causing an atrophy of 

 the apparatus which secretes the silk. The microscope disclosed the supposed morbid 

 element in the shape of small bodies which M. Cornalia designated oscillating 

 corpuscles, and to which M. Guerin gave the inappropriate name of "hema- 

 tozoids." M. Lebert considered them unicellular plants, and Professor Chavannes 

 called them " crystals." M. Cornalia announced, in confirmation of his view, that 

 when worms which died of the disease were exposed to moisture their bodies 

 were covered with a mould whose spores had a remarkable resemblance to the 

 " oscillating corpuscules." But whatever be the real nature of these bodies, their 

 presence is a certain sign of the existence of the disease, and M. Vittadini has 

 made the curious discovery of their appearance in the egg. He tells us that, as 

 soon as the development of the embryo commences, its tissues in diseased speci- 

 mens are filled with the oscillating corpuscules. He has also ascertained that the 

 diseased eggs are developed more slowly than healthy ones, their complete evo- 

 lution requiring four or five days, and even more, instead of two or three. He, 

 therefore, recommends the destruction of all the backward progeny; and, confirming 

 the observations of Marshal Vaillant, M. Quatrefages, and others, he advises the 

 culture of the worms in the open air. M. Chavannes states that if the eggs are 

 developed in the open air upon trees furnished with a metallic trellis, upon which 

 the process may take place, a complete regeneration of the race can be readily 

 effected. 



