Progress of Invention. 399 



R.A.S., Nov., 1862," Mr. Dawes remarks that Steinheil had for 

 some years made an eye-piece, which was apparently identical with 

 the " Aplanatic in construction." 



[We have three of the Aplanatics, and have in our speci- 

 mens very little fault to find with the field almost close to the 

 edge. The " ghost" is, we believe, a reflexion inseparable 

 from the construction. It causes a faint image of a bright 

 object to move one way while the object appears to move 

 in the other. By a little care the image and the ghost may be 

 made to coincide. — Ed.] 



PROGRESS OF INVENTION. 



New Applications of the Syphon. — It has been found, by Mr. 

 Galletly, that different fluids pass through the very same syphon 

 with different velocities — an observation made, indeed, by others ; 

 and also, that the same fluid passes with different velocities through 

 syphons of the same length, but of different bores. Thus, while a 

 vessel of water was emptied by a given syphon in forty-nine seconds, 

 it required eighty-three to empty it of petroleum, and eighty-five to 

 empty it of whiskey. Nor does the result depend, in any way, on 

 specific gravity ; for while paraffin oil was emptied in two hundred 

 and eighty-six seconds, petroleum of the very same density re- 

 quired three hundred and seventy-five seconds. These, and similar 

 experiments, suggested the syphon as a convenient means of ascer- 

 taining the difference between fluids, or the different degrees of 

 purity of the same fluid, a standard vessel and syphon being em- 

 ployed for the purpose. 



Waterproofing by means of Paraffin. — The rendering of tex- 

 tile fabrics, leather, etc, waterproof, has long, and justly, been 

 looked upon as a matter of considerable importance. Many means 

 have, at various times, been employed for the purpose, but all, or 

 most of them, have been found open to objection. Wax and drying 

 oils were the substances first used, then caoutchouc, and afterwards 

 gutta percha, both by itself and along with drying oils ; recently, 

 paraffin has been adopted, but, if used by itself, it crystallizes and 

 separates from the fibres of the cloth, an inconvenience which is pre- 

 vented by the addition of a small amount of drying oil. This 

 mixture possesses the great advantage of rendering a fabric repel- 

 lant of moisture, while at the same time it does not prevent the 

 passage of air through it ; and it affects but little, or not at all, the 

 most delicate colours. It is particularly advantageous to leather, 

 which it not only renders waterproof, but more durable and sus- 

 ceptible of a higher polish. , 



New Mode of Preserving Iron. — In this, which may justly be 

 denominated the " iron age," any effective mode of preserving that 

 metal must be considered of great importance. Almost everything 



