220 Mr. E. H. M. Bosanquet on the 



from the bellows, acting in a way that left nothing to be 

 desired. 



Shafting. — One of the most unpleasant pieces of work that 

 had to be done was the fitting of the supports for the shafting 

 into the walls. The back wall, being brick, was dealt with 

 without great difficulty ; but the front wall is of hard stone, 

 and cutting the necessary holes right through it was a serious 

 piece of work. "What with the laying of the gas- and water- 

 pipes and this, the laboratory was in the occupation of masons 

 &c. pretty nearly the whole of last winter. The shafting is in 

 two lines, each nearly 30 feet long. The two lines are con- 

 nected by a belt about the middle of each. The pulleys are 

 for the most part split pulleys, which can be put on and taken 

 off without disturbing the shafting. This is an arrangement 

 of the greatest conyenience ; indeed, without it no rearrange- 

 ment, such as is often ineyitable, would be possible without 

 serious expense. 



The lathe is by Messrs. Cook, of York. It has five-foot 

 bearers, back gear for reduced speeds, a long screw (with 

 change wheels) for the slide-rest, special apparatus for drill- 

 ing, and cutting the teeth of wheels, and two new arrange- 

 ments of a special character, which were carried out by Messrs. 

 Cooke according to my directions. 



The Micrometer. — This consists of a worm-wheel of 180 

 teeth on the pulley of the mandrel, in which a tangent-screw 

 can be made to engage. The novelty consists of the details 

 of the arrangement by which the turns of the tangent-screw 

 can be subdivided. A number of gun-metal disks are pro- 

 vided, which fit on the tangent-screw. These have different 

 numbers of holes pierced in circles near the rim. Pins are 

 provided which can be inserted in the holes ; a long arm 

 carrying an inverted Y, or perhaps rather a W, in metal, drops 

 over the pin and defines its position accurately. Pointers are 

 provided, which can be adjusted so as to indicate without 

 trouble the hole in which the pin is to be inserted. The 

 pin is inserted into the hole; the screw is turned through 

 so many turns and the fraction over : the W is dropped over 

 the pin last inserted, and the other pin placed in the hole indi- 

 cated by the pointer. This is done after a little practice with 

 great expedition and certainty. I have now divided several 

 circles, and cut several wheels with all sorts of numbers of 

 teeth, and have only, to my knowledge, made one mistake 

 with the micrometer, which was detected at once in time to be 

 remedied. 



The micrometer possesses 20 wheels, whose numbers are as 

 follows : — 



