until at the end of three years of effort he had the white blackberry, which after all was merely to satisfy his curiosity.

Ten years were required to produce a cactus that was without thorns and spines, yet in the production of this species, which shows no disposition to revert to its former armored state, the western desert country may become a paradise for the herds of the rancher. Not only have these cacti become easily edible for stock, but in the processes this desert plant has increased in nutritive qualities as a plant, while the fruit which it bears is of a flavor to appeal to the palate of a Lucullus.

In the consideration of the cactus Mr. Burbank had sought the reason of the thorns. The habitat of the plant being the barren desert sands, where scant nourishment was to be found for itself, and where, on the other hand, the herbivorous creatures that might have need of sustenance might so prey upon it as to destroy the species, the plant had need of its prickly weapons of defense. Putting the plant into an environment where no natural protection was demanded for it, nature was brought to understand that she need not waste her strength upon the growth of a useless armor. For this armor will remain useless when the ranchman once takes the plant under his selfish protectorate.

Burbank's hybrid English walnut is regarded as one of his most extraordinary accomplishments in the development of a food to the best advantages of the needs of man. The English walnut long has been one of the most valuable of after dinner nuts. Those who have not cared for it as a food, ordinarily have found objection to its bitterness. When Mr. Burbank undertook to improve the nut his object was to eliminate the hard husk in the kernel, thus destroying the bitter after taste, to increase the size of the fruit, and incidentally to make the shell thinner. All of this was done to the point of making the shell so thin that the birds broke into the kernels, necessitating the breeding back to a stronger shell. And, above all, he brought the walnut tree to a rapidity of growth and bearing in which it leads any other known tree in the temperate zones of the world. This tree at six months old has borne nuts.

To eliminate seed from a fruit is one of the easy propositions which has confronted Mr. Burbank. To change size and color of a flower and to intensify an odor that has proved pleasing and yet elusive, have been labors of love with him. A seedless prune is an accomplishment appreciated in California horticulture. His plumcot, obtained from the crossing of the plum and prune, is a new fruit with a flavor that is all its own.

From one of his developed plum trees on one occasion 22,000 green plums had to be stripped from the overburdened branches in order that the tree might develop properly its normal load of plums. The late Cecil Rhodes in South Africa received from Mr. Burbank some plum trees which were set out in Rhodesia and from which Mr. Rhodes afterward sent fruit in a basket to Mr. Burbank at San Francisco, the plums arriving in perfect condition after a voyage of 18,000 miles.

How were these things accomplished?

Through a knowledge of plants gained through his own painstaking efforts, many of these serving only to overturn principles and theories that had been advanced by others before him. He recognizes the importance of the old phrases natural selection and survival of the fittest, but above these in importance and effectiveness are the most artificial of crossings.

It is in this crossing of species that he breaks up the tendencies of a plant's life through all its ages of environment, habit, and heredity. Not in the first generation may the sharpest variations appear, but in the succeeding generations those mutations and variations that are prompted by heredity far back into either branch, may be expected to develop, often in wholly unexpected forms. All characteristics which are thus transmitted, he holds to have been acquired, and in the crossing he hastens processes which nature, unaided, might be thousands of years in bringing about.

Mr. Burbank recently has been at work upon the tobacco plant with a view to increasing its size, improving its flavor, and at the same time making it responsive to wider climatic zones. A plant ten feet high, with leaves two feet wide and four feet long has resulted.

HISTORY OF ELECTRICITY IN AMERICA.

BY GEORGE HERBERT STOCKBRIDGE.

[George Herbert Stockbridge, electrical engineer, born July 2, 1863, at Cincinnati, O.; educated at Ohio state university and the Massachusetts Institute of Technology; entered upon the practice of his profession as electrical engineer, to which he has devoted most of his business life, though occasionally writing articles for technical and general periodicals.]

It happens that the first great name in electrical science in America is one of the first and greatest in electrical science everywhere. Benjamin Franklin began to devote himself to electrical studies at a time when scarcely more than half a dozen investigators had contributed anything of permanent value to the science; while his hypothesis of a single electrical fluid subsisting in positive and negative states marks a turning point toward the modern science, and his demonstration of the identity of lightning and electricity outranks in popular and scientific interest every experiment before or after, prior to the discovery of current electricity by Volta and Galvani, fifty years later. Priestly says of his theoretical work: "Dr. Franklin's principles bid fair to be handed down to posterity as equally expressive of the true principles of electricity, with the Newtonian philosophy of the true system of nature in general." Beyond such praise as this it is impossible to go; but Dubourg justifies it when he says that the doctrine of Franklin taught us to discriminate and to foresee. The course of scientific progress from the beginning until now has been lighted from point to point by a few golden lamps answering to that simple touchstone of Dubourg's. No wonder Priestly thought of comparing Franklin to Newton, as an Italian might have likened him to Galileo, or a German to Kepler and Copernicus.

The circumstance that Franklin's work was done in the early and elementary days of electrical knowledge adds to the audacity of his famous experiment with the kite; which quality was, indeed, from the first, one of the chief reasons for the great popularity of that particular piece

of history. Franklin was fortunate in having demonstrated an important scientific truth in a manner which appealed to the imagination, and for this reason the unscientific mind was more impressed by it than by any other discovery in natural philosophy during the 18th century. "The Philadelphian experiments," says the Abbé Mazéas, in a letter which was read to the Royal Society in May, 1752, "having been universally admired in France, the king desired to see them performed."

It has been characteristic of electrical discoveries from the beginning that they have lent themselves to startling effects; but this experiment of drawing lightning from the clouds involved the human interest quite as strongly as the scientific. It was not alone a scientific achievement; it was an act of personal daring which, in the public mind, at least, approached very near to the moral sublime. Hence it is the one portion of electrical history with which everybody is familiar.

The earliest reference in Franklin's writings to the notion which afterwards led to his experiment appears in his note book, under date of November 7, 1749, as follows:

Electrical fluid agrees with lightning in these particulars: 1. Giving light. 2. Color of the light. 3. Crooked direction. 4. Swift motion. 5. Being conducted by metals. 6. Crack or noise in exploding. 7. Subsisting in water and ice. 8. Rending bodies it passes through. 9. Destroying animals. 10. Melting metals. 11. Firing inflammable substances. 12. Sulphureous smell. The electrical fluid is attracted by points -we do not know whether this property is in lightning. But since they agree in all the particulars wherein we can hardly compare them, is it not probable that they agree likewise in this? Let the experiment be made.

At this time, Franklin had been engaged for nearly three years in the most absorbed pursuit of electrical experimentation, which commenced when his friend Peter Collinson, a Fellow of the Royal Society, sent from London to the Library company in Philadelphia an "electrical tube," about the beginning of the year 1747. In a letter to Collinson, dated March 28, of that year, Franklin declares that

་

he has already become wholly given up to the study of electrical phenomena. He says:

"For my own part, I never was before engaged in any studies that so totally engrossed my attention and time, for what with making experiments when I can be alone, and repeating them to my friends and acquaintances, who, from the novelty of the thing, come continually in crowds to see them, I have, during some months past, had little leisure for anything else."

From this time on for several years, his letters to Collinson are filled with wonderfully clear details of numberless experiments coupled with brilliant deductions and speculations of a scientific nature. Here, in this offhand, private correspondence, Franklin sets forth the doctrine which was to change permanently the course of electrical science, and describes the most remarkable electrical experiment that was ever tried.

Through Collinson, accounts of Franklin's work were laid from time to time before the Royal Society, where, however, they excited little favorable attention, and in some instances derision. Franklin's suggestion of the possibility of rendering lightning discharges harmless by conducting them through an easy medium to the earth was the subject of special hilarity on the part of Collinson's learned associates. Collinson himself seems to have held his friend's labors in high esteem. At all events, through him Franklin's letters were published in London, though without the authoritative inscript of the Royal Society. In this form, or, rather, in the form of a bad French translation, they came under the eye of the celebrated French naturalist and philosopher, Buffon, who at once saw their value, and advised that an accurate translation be made. And the reputation which Franklin thus, and by his later scientific work, acquired in France contributed not a little to his influence in after years when he appeared at the court of Louis the Sixteenth in the rôle of a diplomat.

It was in this roundabout way that the French savants learned of Franklin's determination to test the identity of electricity and lightning by actual trial; for, closely follow