The ship designer has to work within circumscribed limits. If he could make his vessel of any depth he might build much larger and there would be theoretically no limit to his speed: 40 knots an hour might be obtained as easily as the present maximum of 26, but in designing his ship he must remember that in the harbors of New York or Liverpool the channels are not much beyond 30 feet in depth. High speed necessitates powerful engines, but if the engines be too large there will not be space enough for coal to feed the furnaces. If the breadth of the ship is increased the speed is diminished, while on the other hand, if too powerful engines are put in a narrow vessel she will break her back. The proper proportions must be carefully studied as regards length, breadth, depth and weight so that the vessel will derive the greatest speed from her engines. CHAPTER VII WONDERFUL CREATIONS IN PLANT LIFE Mating Plants--Experiments of Burbank--What he has Accomplished. In California lives a wonderful man. He has succeeded in doing more than making two blades of grass grow where grew but one. Yearly, daily in fact, this wizard of plant life is playing tricks on old Mother Nature, transforming her vegetable children into different shapes and making them no longer recognizable in their original forms. Like the fairies in Irish mythology, this man steals away the plant babies, but instead of leaving sickly elves in their places, he brings into the world exceedingly healthy or lusty youngsters which grow up into a full maturity, and develop traits of character superior to the ones they supplant. For instance he took away the ugly, thorny insipid cactus and replaced it by a beautiful smooth juicy one which is now making the western deserts blossom as the rose. The name of this man is Luther Burbank whose fame as a creator of new plants has become world wide.