[JAN. 



VARIETIES, SCIENTIFIC AND MISCELLANEOUS. 



Perkins's Steam. Machinery. After all 

 that has been conjectured, and insinuated, 

 and surmised, and written about Mr. Per- 

 kins's modifications and improvements of 

 steam machinery, we are happy to give 

 from his own pen the following summary 

 of them, which is abridged from a most 

 interesting article inserted in one of the 

 scientific journals of America, the land 

 that gave him birth. Is it not new, he 

 inquires, to generate steam of all elasti- 

 cities, from the minimum to the maximum 

 without the least danger in the genera- 

 tion of steam to substitute pressure for 

 surface, which he considers the basis of his 

 invention to have a pressure of lOOOlbs. 

 to the square inch on one side of the pis- 

 ton, while on the other side of it all re- 

 sistance is taken away by a vacuum, and 

 this produced without an air-pump, or any 

 more water than is used in generating the 

 steam to have invented a metallic piston, 

 which requires no lubrication, and yet is 

 as tight as the piston of an air-pump to 

 have applied Davy's zinc protectors to 

 steam cylinders to prevent oxidation,which 

 took place when the engine was not at 

 work to dispense with the eduction valve 

 and pipe, having no other than a small 

 induction valve, and that so constructed 

 as to neutralize the pressure, requiring no 

 oil, and very little power to open and to 

 close it to allow steam to escape at an 

 opening 250 times larger than the steam 

 pipe ; and lastly, to have discovered that 

 steam may be generated although in con- 

 tact with the water, at all temperatures, 

 without producing corresponding elasti- 

 city? In the steam artillery, which this 

 eminent engineer is constructing for the 

 French government, he guarantees the 

 perfect safety of the generator, its inde- 

 structibility, the ability to keep the steam 

 up at any required temperature for any 

 length of time, and its great economy. 

 The piece of ordnance is to throw sixty 

 balls of four pounds each in a minute, 

 with the correctness of the rifled musket, 

 and to a proportionate distance. A mus- 

 ket is also attached to the same generator 

 for throwing a stream of lead from the 

 bastion of a fort, and is made so far port- 

 able, as to be capable of being moved from 

 one bastion to another. This musket is to 

 throw from one hundred t one thousand 

 bullets per minute as occasion may re- 

 quire, and that for any given length of 

 time. As regards economy, it is within 

 the truth, that if the discharges are rapid, 

 one pound of coals will throw as many 

 balls as four pounds of powder. The mis- 

 chief of this steam artillery is that it will 

 be to nations what the pistol is to duel- 

 lists, it will bring all, whether strong or 

 weak, upon a par. Among the very cu- 



rious results from Mr. Perkins's experi- 

 ments upon steam is one, which proves 

 practically what Dr. Hare, of Philadel- 

 phia, has so ably attempted to establish 

 theoretically, namely, that caloric is mat- 

 ter. The proof, he says, is simple and 

 direct, and, I am persuaded, conclusive. 

 Mr. Perkins's explanation of the bursting 

 of boilers will appear very plausible it is 

 this: that the water is suffered to get so 

 low as to bring a portion of the boiler not 

 covered with water in contact with the 

 fire ; this becomes red hot, and imparts its 

 heat to the steam; the redness gradually 

 extends itself below the water, which is at 

 length repelled from the water and thrown 

 up among the hot steam (like a pot sud- 

 denly boiling over), which overcharged 

 steam immediately imparting its excessive 

 heat to the water, forms steam of the 

 greatest power, and occasions the disas- 

 trous explosion. 



Timbuctoo. At one of the last meetings 

 of the Geographical Society of Paris, an 

 interesting communication was made re- 

 lative to Timbuctoo, the Atlantis of the 

 moderns. It was stated that a detailed 

 history of this city was in existence, writ- 

 ten by Sidi-Ahmed-Baba, a native of Da- 

 rawana, a small town in the country of 

 the Rentes. It is therein stated that its 

 foundation was not prior to the year 510 

 of the heg-ira (1116 of our aera). The 

 Arabian author attributes its origin to a 

 woman named Buktou, of and belonging 

 to the horde of the Touaries, who at first 

 established herself on the banks of the 

 Nile of the negros, in a cabin sheltered by 

 an umbrageous tree. She possessed a few 

 sheep, and was fond of displaying hospi- 

 tality to the travellers of her nation. Her 

 humble habitation soon became a sacred 

 asylum, a place of repose and enjoyment 

 for the neighbouring tribes who called at 

 Tin-Buktou, that is the property of Buk- 

 tou. In the end various tribes established 

 themselves there, and made a vast en- 

 trenched camp, which subsequently was 

 transformed into a great and populous city. 

 Of the races which compose the inhabi- 

 tants of this city, it may be remarked, that 

 it formerly belonged to the Kohlans (a 

 pagan people) ; it is now occupied by the 

 Fellars, followers of Mohammed. The 

 Touaries form a third race j a fourth is 

 that of the Rentes, who are supposed to 

 have come from Bambara. 



Theory of Flame .Sir H. Davy ascribes 

 the security which the safety lamp affords, 

 to the conducting power of the metallic 

 gauze, by which it is supposed the tempe- 

 rature of the flame is so much lowered as 

 to be insufficient to ignite the inflammable 

 mixture on the outside. Some facts known 

 to Signior G. Libri, of Florence, were at 



