Another source for notions of this same sort, as to the unreliability of submarine navigation, is the constant repetition in the daily press that our submarines are not operating satisfactorily. These complaints also lead people to conclude that the mechanical demands of under-water navigation are not completely fulfilled. Now, submarine vessels may be constructed to-day which are a great deal more trustworthy in their operation and considerably less dangerous to go about in than are certain well-known United States railroads. Nearly every submarine in use in the navies of the world at the present day is capable of functioning in perfect safety, so far as submergence and emergence are concerned. They may be operated with almost exact precision while located many feet beneath the surface. If given sufficient static stability, there is no danger that they will dive to the bottom or that they will not come up again. The cause of all these complaints about our submarines is traceable to a single difficulty. The reader by this time realizes that the difficulty is with the engines, and not with the principles of submarine construction. The modern submarine builder cannot find an engine of sufficiently light weight to install with safety in a submarine hull which will give all the speed which the government demands that his boat should produce. On attempting to attain speed much engine trouble has developed, due to experimentation and trial, and from this source have sprung all the criticisms of the operation of our vessels. There is no such natural limitation to the possible utility of the submarine as many people believe; the only limitation is that of speed. Our boats are safe, they are seaworthy, they are capable of a tremendous radius of action. Sooner or later a reliable engine will be developed which will meet the needs of military submarines and which will deliver power sufficient to give the submarine battleship speed. This is at present the only limitation upon submarine development, and it is not an insuperable obstacle.