Naval Architecture and Ship Building 117 



difficult nor abstruse but much ingenuity has been expended in devising 

 simple forms and methods for ship calculation. 



In spite of our desire for shortening work, it is usually regarded as 

 essential that forms of such work should contain an automatic check. 

 For instance, when determining the volume of a ship below water we 

 calculate the areas of a series of transverse sections and then sum them 

 longitudinally and from the same original ordinates calculate the areas 

 of a series of horizontal sections and then sum them vertically. If 

 the identical result is obtained by the two methods we naturally con- 

 clude it is correct. I recall, however, one example in my experience 

 where such a result was wrong. Intermediate errors produced the ident- 

 ical error in each result. Fortunately it was not material. 



To instance another application of mathematics. It is this science 

 in the end which has made possible the modern systems of control of the 

 firing of the great guns which permit them, with a considerable degree 

 of accuracy, to drop a shell weighing as much as a ton on a com.para- 

 tively small target at distances of twelve to fifteen miles. If the ship 

 and its target were both fixed, mathematics would play a comparatively 

 small part. The range finder, developed from the science of physics, 

 would be the primary factor involved, but when a shell has to spend 

 many seconds in the air (nearly half a minute at extreme ranges) from 

 the time it leaves the gun until it reaches its mark, when the firing ship 

 and the ship fired at are moving at variable speeds, each with a possible 

 angle of 360 degrees in azimuth, even an accurate knowledge of the dis- 

 tance separating the ships firing and fired at, at the instant of firing or a 

 short time before, is of comparatively little value. Other variables 

 mentioned above, all come in and the accurate control of fire of the pres- 

 ent day is based largely upon instruments or mechanisms which permiit 

 the instantaneous solution of problems containing as many as half a 

 dozen variables. 



Chemistry is a science just as important in shipbuilding as any 

 other branches of engineering. For men-of-war the problems involved 

 in the manufacture of propellent powders and high explosives in safe 

 and desirable forms are essentially chemical problems. Chemistry, 

 also, is essential in metallurgy, which plays one of the most important 

 parts in shipbuilding by providing numerous varieties of steel, ferrous 

 alloys and non-ferrous metals, which are used in the various parts of 

 the ship and its equipment. Of course most of these materials are in 

 general use but some of them have been developed solely for the use to 

 which they are put on ships and there are many peculiar chemical 

 problems. I recall one case which illustrates such a problem. As we 

 all know, aluminum has extreme lightness and adequate strength for 



