86 Laboratory Arts 



jackets, eudiometers, voltameters, and similar pieces of appa- 

 ratus. Personal instruction is, of course, much to be preferred 

 to descriptive text-book instruction, but such details will be 

 found in the subsequent pages as will enable a student to pro- 

 gress as far as that stage at which he experiments upon method 

 for himself, and when this stage is reached, further instruction 

 is unnecessary. 



It cannot be too strongly impressed upon a beginner that 

 for a time he will be thoroughly dissatisfied with his results, 

 and that nothing but constant repetition will enable him eventu- 

 ally to master the nature of his material so as to produce 

 whatever he desires. Once this point is attained, however, his 

 progress will amaze him. 



Curiously enough, one's skill appears to vary from day to 

 day. On some days one may dare all things successfully, 

 while on others each attempt at even a simple exercise ends 

 in failure. In the latter case, rest is the only cure. On the 

 other hand, skill once acquired appears to lie dormant during 

 comparatively long periods without sensible loss, though, of 

 course, no progress will so be made. 



The actual physical skill necessary in glass-blowing is small, 

 the muscular training necessary to secure a perfectly steady 

 hand and arm, and to enable one to revolve a tube steadily 

 and regularly without altering the position and direction of its 

 axis, being almost the summation of the physical requirements. 

 The ability to blow and work glass successfully is acquired in 

 consequence of 



1. A knowledge of every trick and possibility of the 

 blowpipe, and of how to secure any desired condition instantly. 



2. A knowledge of what the material can and cannot do, 

 and of the outward signs by which its suitability for various 

 treatment may be recognized. 



3. A spirit of daring, to take instant advantage of a condi- 

 tion immediately it is recognized. 



Some forethought is also necessary, to have handy all 

 pieces of apparatus, tools, etc., and to arrange so that a hot 

 piece of glass need never be put down while a subsidiary piece 

 is being made. 



