20 



HARDWOOD RECORD 



to dimensions suitable for convenient hand- 

 ling, as shown in figure 1. Then the sizes 

 of the pieces for the individual tops are 

 marked off by means of the try-square. 

 These pieces are turned down to the desired 

 cone-shaped size on a regular turning lathe, 

 instead of being chipped tediously by hand, 

 as in the past. The speed with which the 

 tops can be turned down on the lathe after 

 the pattern is once set is surprising. From 

 one to twenty tops can be turned at one time. 

 Quite a little mechanical draughting is neces- 

 sary in order to develop the defining lines 

 for the forms of modern hardwood tops. A 

 regular constructive sketch is now used, 

 draughting paper being often employed to 

 assist in defining the lines for the shaping 

 of the top. The squared paper is used in 



^>°° 



$& 



some shops, while in others the plain descrip- 

 tions are preferred. Bond paper about 20 

 by 30 inches, ruled or unruled, makes good 

 material. The surface of this paper is hard 

 and suitable for the w T ork. 



In developing a curve for the defining line 

 of the top a scale may be made, and the 

 pattern made by the oblong a, b to c, as in 

 figure 2. A compass is needed and some 

 wood scroll patterns to help make the curve. 

 The two ends are simple parabolic curves, 

 one of which is shown. The dimension lines 

 can be drawn with neutral color if desired, 

 in order to make a distinction. The elements 

 of the circle can be secured as in figure 



4, and then can be applied to the form of 

 the top as on the line d, figure 3. The essen- 

 tial elements of the circle, figure 4, may be 

 classed as the circumference, the diameter, 

 the radius and the section. The chord, seg- 

 ment, quadrant, zone or tangent in the curved 

 sided top will hardly be needed. However, 

 it is well to have these elements in readiness 

 and charted off. In figure 5 the use of the 

 radius, the sine, the cosine, the tangent, the 

 cotangent, and the like may be required. 

 These lines may be defined as per the cut, 

 and it will be of assistance to construct an 

 instrument of the character presented in fig- 

 ure 6. This consists of a straight, even stick, 

 like a rule, about three feet long, quarter of 

 an inch thick and three inches wide. Then 

 construct a sheet brass circle describing the 

 form with a slot e. Fasten this to the rule 

 f with a pin. Then mark off the rule in sec- 

 tions, and using the pin as the pivot, the 

 circular piece can be swung to any desired 

 angle for the making of curves for tops in 

 connection with the circles previously men- 

 tioned. The proper circumferential pitch 

 can be obtained with these contrivances, as- 

 sisted by the common try-square, as in fig- 

 ure 7. The steel square is a very useful 

 tool in the designing department of the top 

 manufacturer. The fixed points on the plan 

 of the top as at g and h are secured. A 

 line can be drawn through the tangent line, 

 straight across, and define the tapering side 

 of one edge of the pattern by means of the 

 steel square. A variety of angles may be 

 struck, and each defined separately and 

 marked off for the final form of the top de- 

 sign. Some of the hardwood tops are grooved, 

 as illustrated in figure 8. Then some of them 

 are of the common cone shape, one of which 

 is demonstrated in figure 9. The top in fig- 

 ure 10 is known by the sporting element as 

 the fighting top. The contestants in the 

 game fix their tops with the metal balls and 

 the steel point. A number of tops are thrown 

 by the players, each trying to strike the tops 

 of the other contestants and split one of them 

 with the steel point of his heavy top. Then 



there are tops with curved, snake-like necks, 

 as in figures 11 and 12. These styles of tops 

 are worked out mostly by hand. 



The actual processes of hardwood top- 

 making include the diagraming of the plans, 

 as illustrated. Then the pieces of wood are 

 carefully turned down according to these 

 pen and ink diagrams. Then the steel 



points are inserted, followed by the smooth- 

 ing and polishing of the tops. This is 

 done on the turning machines, while burnish- 

 ing devices are held against the revolving 

 surfaces. The cheaper tops are burnished in 

 revolving cylinders, by rolling a number of 

 them in fine emery. 



In the School of Experience. 



Proportions of Concrete. 



The National Builder gives the following pro- 

 portions for concrete of varying strengths which 

 are supplied by a leading cement house : 



One part Portland cement, 2 parts sand, 4 

 parts broken stone give the strongest concrete 

 made. 



One part Portland cement, 2% parts sand, 5 

 parts broken stone give an exceedingly strong 

 concrete, suitable for foundations of sidewalks, 

 engine foundations, etc. 



One part Portland cement, 3 parts sand, 6 

 parts broken stone offer an exceedingly strong 

 concrete, suitable for carrying a "sky-scraper." 



One part Portland cement, 4 parts sand, 8 

 parts broken stone furnish a sufficiently strong 

 concrete for ordinary purposes. 



One part Portland cement, 5 parts sand, 10 

 parts broken stone make a cheap concrete, strong- 

 er than concretes from common cements. 

 Laying and Nailing Floors. 



The fact that the floors of buildings are 

 scarcely secondary in importance, as a feature 



of strength, their being properly nailed becomes 

 a material matter for consideration. No one 

 who understands the science of construction will 

 undertake to question the value of floors in 

 buildings as a means of bracing and stiffening, 

 either in brick or frame constructions. And this 

 fact being admitted, the question of the best 

 method of laying and nailing them becomes im- 

 portant. Yet there is no portion of the work, 

 as a rule, more carelessly executed, except where 

 care becomes an obligatory and imperative neces- 

 sity in special eases. To lay floors properly they 

 should fill out snugly to the walls at all parts. 

 The more solidly this is done, the more complete 

 will be their bracing effect. Every piece of tim- 

 ber used in a building has a proportionate 

 strengthening value, and that value is increased 

 or diminished by the manner in which each piece 

 is applied and secured. Every single nail driven 

 is one part of the general strength obtained, 

 although one nail is very insignificant considered 

 in connection with the thousands used in a 

 building. One or two or a hundred may be 

 omitted, and apparently no harm will result; 



