14 Laboratory Arts 



wood entirely ; whereas glue used of proper consistency or 

 strength will pull away pieces of the wood rather than break 

 at the joint. 



Glue deteriorates every time it is melted, consequently it is 

 well to make frequently, and keep free from dust and shavings, 

 etc., which, being gritty, prevent the wood surfaces coming into 

 good contact. 



Two pieces of wood to be jointed should first have their 

 surfaces planed to a perfect contact. One piece should then 

 be firmly gripped in the vice, surface upwards, and the other, 

 inverted, i.e. surface upwards also, held alongside. The glue 

 should then be quickly and evenly spread along the two sur- 

 faces, the second one quickly erected into position, and rubbed 

 backwards and forwards several times along the fixed piece. 

 Presently it will become difficult to move, when it should be 

 finally brought to its desired position, and allowed to " dry " or 

 " set." Cramping is usually unnecessary if the above method 

 is adopted. 



Nails and Screws. Nails should rarely be used in 

 apparatus making. Wood joints, well glued, will repay the 

 time spent upon them, and where metal junctions are necessary 

 screws should be used. In large and rough pieces of apparatus, 

 however, nails are at times permissible, in which case oval steel 

 " brads " should be used. These can be obtained in sizes from 

 J" to 3", and having the advantage of being oval, rarely split 

 the wood. Moreover, they can be driven fully into the wood, 

 and so become practically invisible. 



Round " wire " nails (French nails) and " cut " nails should 

 be avoided, being clumsy and not holding well in work adapted 

 for laboratory use. Cabinet makers' " veneering pins " are 

 sometimes useful, as also are " gimp tacks " for special pur- 

 poses, but it may be taken that as a general rule the use 

 of nails is to be deprecated. It is, in apparatus, the sign of 

 slipshod work. A cabinet maker frequently makes the state- 

 ment : " There is not a nail in it," as a proof of good work, and 

 apparatus should at least be as well made. Sometimes he goes 

 further, and says : " There is not a bit of metal in it," but there 

 we cannot follow, as we are accustomed to take advantage of 



