Bkckkb — A New Principle in Blowpipe Construction. 279 



A sectional drawing of the experimental blowpipe which has been made 

 to embody and test this principle is given in fig. 1. The instrument consists 

 of two moving and one fixed part. The member which controls the air- 

 supply is marked A in the drawing, and consists of a cylindrical block of 

 brass, in which are drilled eight radial passages for the aii', which com- 

 municate with eight air-jets. These air-jets are sjmced equidistantly lound 

 the circumference of a deep recess formed in the brass cylinder. This recess 

 is divided into eight equal spaces by eight brass partitions, thus forming the 

 spaces for the gas to surround the air-jets. 'J'he gas has access to these 

 spaces through a number of radial holes drilled in the brass cylinder, as 

 shown in the sectional side elevation in fig. 1. The outer circumference of A 

 is turned taper, and ground to fit the corresponding part of B, and it also 

 has a deep conical hole bored in it for more than two-thirds of its depth, 

 which is also ground to fit the corresponding portion of B. 



The part B consists of a thin brass disc, carrying on its periphery a thin 

 hollow cylinder, which is ground taper to fit the outer circumference of A, 

 and is provided with eight apertures through which the flame is projected. 

 This disc also carries a projecting portion near the centre, which has two 

 conical surfaces, the outer fitting the conical hole in A, the inner fitting the 

 corresponding tapered portion of 'C. 



In this double conical portion of B there are drilled a number of equally 

 spaced holes, which, by their size and number, vary the amount of gas 

 admitted to the blowpipe. Two of these holes are indicated in the part- 

 sectional side elevation (fig. 1). 



The fixed portion C also consists of two oppositely tapered cones, the 

 right hand one being tapered to fit B, and having a passage for the gas 

 formed in it at one place, the other being tapered to fit the inner circum- 

 ference of A, and provided with a passage for the air so placed as to 

 correspond with that for the gas. 



The portions A and B are free to revolve, both with respect to each 

 other and with respect to C, but a small spring catch secures A in any 

 desired relative position with respect to B, the two then revolving as a solid 

 mass round C. In this way any desired air-jet on A can be brought opposite 

 any gas-jet on B at will. 



When A and B are locked together in any position, the revolution of the 

 whole round C gives eight flames of different sizes between about one inch 

 and twelve inches in length, and each of these flames is formed by an air-jet 

 of just the right bore for its particular requirements ; thus the bore of the 

 largest air-jet is about •125 inch, and that of the smallest about '015 inch. 



A by-pass is provided, which is opposite the passages bored in C, and 



