. Cassier's magazine. s of design is alsostudied in many ways, as in keepingtool boxes as closely as possible to theirslides, in bringing beds and screws closeto the areas of severest stress; and wherethis is not practicable, then it becomesnecessary to receive the strains on slidesof ample width and length in order toprevent jerky movements and lost mo-tion. Mass, again, involves casting inpieces, because single castings of ab-normal dimensions are difficult to make, as is frequently done in the case of smallmachines, engines, and cranes. It isdifficult to make massive castings, be-cause they
. Cassier's magazine. s of design is alsostudied in many ways, as in keepingtool boxes as closely as possible to theirslides, in bringing beds and screws closeto the areas of severest stress; and wherethis is not practicable, then it becomesnecessary to receive the strains on slidesof ample width and length in order toprevent jerky movements and lost mo-tion. Mass, again, involves casting inpieces, because single castings of ab-normal dimensions are difficult to make, as is frequently done in the case of smallmachines, engines, and cranes. It isdifficult to make massive castings, be-cause they require special tackle in thefoundry, powerful cranes, big core-dry-ing stoves, cupolas, or receivers of largecapacity, and large doors for exit. Itis equally difficult to handle them in themachine shop, some of the reasons forwhich are similar to those just noted inthe foundry, while another is that themachine tools are too small to deal withcastings of abnormal dimensions exceptby the adoption of makeshift VIEW OF THE 16-INCH GUN LATHE SHOWN OPPOSITE to handle, to tool, to fit up, and totransport when finished. There is novirtue in casting big work whole, thoughsuch jobs are something to be proud properly built-up casting is just asrigid and useful as one that is cast en-tire, and it is generally more likely tobe sound throughout. A big wastedcasting is a proportionately heavier lossthan a sectional one. A fracture, too,either during erection or while in use,is of less moment if the frame of a ma-chine is in sections, which can be read-ily replaced without great expense ordelay, while a break in a big casting isa serious thing. The problem is wholly different fromthat of casting numerous parts together, The fastening of the sections of aframework together is an importantmatter, rigidity, and immunity fromshifting, relatively, being contact surfaces must be broad,provided in many cases with shouldersor tongues to prevent lateral movement,and held
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