To the Editor of the SCIENTIFIC AMERICAN: Just a few lines concerning the article in the SCIENTIFIC AMERICAN for January 21st on the Utilization of Solar Radiation and Wind Power. It was somewhat surprising that the leading American scientific journal should give space for an article and full-page illustration on such an impossible proposition as this. The inventor of this interesting device, Mr. R. A. Fessenden, proposed to cover an artificial lake with thick glass. He expects the sun's heat will convert the water in this lake into steam with which to drive an engine! Now any schoolboy knows that the rays of the sun can never raise water to the boiling point of 212 degrees without the use of condensing mirrors or lenses. The solar steam engine is not practical, and never will be, owing to the expensive machinery of such a plant and the small and erratic nature of the power obtained therefrom. There have been described in the SCIENTIFIC AMERICAN several solar engines. One of these, located in California, I think, uses a huge parabolic mirror to converge the sun's rays upon a small boiler placed in the center of the apparatus. A train of gears and clockwork is used to keep the whole affair constantly pointed at the sun as it travels from east to west across the heavens. A steam pipe carries the steam thus generated to a small engine, which gives 8 or 10 horse-power. This machine undoubtedly works, but the mechanism is complicated, delicate, and costly, and probably requires the constant care of an engineer. It is probably far from an economical power plant. Of course, it operates only when the sun shines. Another device of similar nature, instead of using water in the boiler, uses ether or some, other liquid witn a lower boiling point than water. This obviates the use of mirrors, but the loss of the generating liquid must be considerable, even with the use of the best condensers, while the power obtained in this way is small in quantity and uncertain in nature. Mr. Fessenden's second scheme, which consists in using windmills to pump water into storage tanks, from which it is drawn to operate turbines and generators is more practical than the solar device. But why not drive electrical generators directly from the windmills, and store the power thus produced in efficient storage batteries? This is already being done in several places, and for small plants seems to work fairly well. It is certainly much less wasteful of energy than the water-storage-turbine system would be. By the way, what has become of the page for corespondence formerly contained in your esteemed paper? This was a very interesting feature, and I trust is not going to be discontinued. Your paper is certainly greatly improved slince the new year, and your efforts are sure to be appreciated by your army of readers. DEWEY C. CANFIELD. East Canaan, Conn. Longer Piers at New York To the Editor of the SCIENTIFIC AMERICAN: In your article of February 4th, on the "Longer Piers" controversy at New York, and the ,editorial on the same subject, you cover the ground exceedingly well but for a few points which should not be neglected, and which require no argument. The origin of the controversy was as follows: One of the great foreign companies, operating to this port, came to the government at the eleventh hour saying that they were just completing a great new ship and wished to encroach 100 feet on the fairway for .her accommodation. The present pier head line was established by competent government engineers for the best interests, not only of the port, but of the river and of the whole country, and its establishment was to safeguard the future. Twice before this, corporate and local interests have sought to encroach beyond this line and twice they have failed and made other satisfactory arrangements. Such arrangements can be made perfectly well now, and the petitioning companies and the Department of Docks and the government engineers all know it. Below West 41st Street and above West 44th Street are considerable stretches available for piers. The stone bulkheads are not yet built in these places and the general character of what pters are there is more or less temporary. By keeping the bulkhead about where the old bulkhead was and now is, and by skewing the piers a little, they could easily be made 1,000 feet long. The talk of these larger ne,w ships going to any other port than New York is hardly worth a busy man's thought. New York is the only place that can give commerce of the quantity and class required. If New York should get 100 feet extended into the fairway the Jersey Commission would demand the same thing. Larger ships are surely coming if past records show anything, and larger ships certainly need a commodious harbor. Again, besides the larger ships the aggregate commerce will be immensely larger in twenty years, and it would seem criminal to congest the harbor or take away any of the lee-room which it now enjoys. Comparison of Liverpool or other harbors is meaningless without comparing also the character of the harbor traffic, and in no other harbor of the world can such an intricate, crisscross, complicated traffic be found as in New York. We have the best harbor in the world, and it is the business of the engineers of the government to maintain it. They are responsible to no parties or corporations or private interests, and the measure of their responsibility rests only in their own judgment of the future welfare of the port, the river and the country. By holding up their hands we will be doing an act for which the future will bless us. New York, N. Y. BOAT'MAN. A Mechanical Problem of Puzzling Interest." To the Editor of the SCIENTIFIC A^IERICAN: Will you kindly submit to the readers of the SCIENTIFIC AMERICAN the following mechanical problem, which I believe to be of some puzzling interest, even if it looks so simple? I have not seen two persons that give the same quotation or figure it out in the same way: I, II, III are three distinct problems, and may represent three independent sets of rollers or three sets of planetary gear movements. A, A', A" are internal gears. The figures (111, 25, 61) (111, 37, 37) and (111, . 45, 21) are the number of teeth upon the different gears. The questions are: I. If internal gears A, A', A" are held stationary, how many revolutions are required of gears (C, 61). (C, 37), and (C, 21) to carry satellite gears (B, 25), (B, 37), and (B 45) one revolution around internal gears A, A', A", or back to the starting point marked by arrows? II. If vice versa, gears (C, 61). (C, 37), and (C, 21) are held stationary, how many revolutions are required of internal gears A, A', A" to carry satellite gears (B, 25), (B 37), and (B, 45) one revolution around stationary gears (C, 61), (C, 37), and (C, 21)? III. Which is the simplest solution or key to the problem? Chicago, Ill. JOSEPH DE MARTINO. Spread of the Rural Telephone Movement THE movement for communication among farms and for better connections between rural and city districts has increased wonderfully within the past few years. To those who are ignorant of the real statistics, the figures of the latest telephone census are amazing. For the period from 1902 to 1907 the number of rural telephone stations in the entire country increased 449 per cent. In 1902 there were but 266,966 rural telephone stations in the United States; five years later there were 1,464,773. The census figures show that the South has a great share in this development. The increase in the South Atlantic States was 469 per cent, and in the South Central States it was 367 per cent. The actual figures, however, mean more than percentage, showing steadily increasing telephone development in all States. Wherever the telephone has gone it has brought with it better living, an increase in the productiveness of the farms, and money-making opportunities for the agriculturist that were not dreamed of before. But when one considers that in this five-year period the number of rural telephones jumped from 94 to 5,073 in Maryland; from 270 to 24,874 in Oklahoma, and from 159 to 12,403 in Arkansas, the manner in which telephones were popularized and raised from the station of a rich man's luxury to that of an every-day necessity of all the people can be readily understood. The census, though its results have only recently been published, does not bring the actual conditions quite up to date. No figures are available for the year and a half since December 31st, 1907, but the increase in the number of rural telephone stations has been even more marked than in the five-year period to which the statistics refer. The reasons for this growth are not hard to find. Life on the farms used to be irksome--distances were so great. The telephone is the annihilator of distance. As one farmer expressed it, "I am next door to everybody I want to talk to. That telephone puts my isolated farm in the heart of things." Roosevelt's Country Life Commission designates the telephone as one of the foremost influences making for the solution of the rural problem. When it is considered that the average farmer can install this advance agent of development at a cost less than the present return from a bale of cotton, or thirty bushels of wheat, it is not difficult to understand why the rural telephone is making great strides throughout the entire country. The part which the farmers themselves have taken in the telephone movement makes it one of considerable importance. It is a fact that for very small trouble and expense a group of neighboring farmers can buy, build, and maintain a serviceable telephone system. The work of installation is not so very different from ordinary fence-building operations about the farm. Equipment conforming with the best recognized standards is at the disposal of progressive rural citizens for their telephone building. It is not an unusual sight to witness gangs of farmers at work on the roads, erecting poles, stringing wires, and installing the instruments in the farm-houses along the countryside. This work is usually done on a co-operative basis. Often some sort of an organization is formed. Sometimes six or eight neighboring farmers start the movement. In case there are as few as this, no switch-board is necessary. Construction and maintenance are of the simplest nature. A single pair of wires will suffice, and the "party line" system is found the most convenient and useful. As demands grow and the little rural companies branch out, extensions are made, and, usually, connection through trunk lines with the rest of the world. It is interesting to note that the adoption and development of the telephone in a rural locality is attended by a minimum of expense. Of all the agencies that help bring greater opportunities to the farms-- the goods road movement, railroad extensions, the rural mail delivery, and the farm telephone--the least costly, and, because it reaches the largest number, the most important, is the telephone. No longer does the farmer consider "the voice in the box" as one of the mysterious things for the city fellow to fool with, and for the farmer to let alone. The ease and small cost with' which the neighborhood telephone line can be constructed appeals to and interests him. Manufacturers of telephones, and operating telephone companies generally, publish books and pamphlets describing "How to Build Rural Telephone Lines." These publications treat the subject in a simple and comprehensive way; they are profusely illustrated in a way which enables any one with ordinary intelligence to construct a practical telephone line of a limited number of stations. Increasing Use of Automobiles by the Farmers A CCORDING to the Bureau of Statistics at Washington, a careful compilation of all available returns has shown that last year the farmers of this country purchased 26,000 automobiles--an increase of 85 per cent over the previous year and more than 400 per cent over the number of cars purchased by them in 1909. The farmers of the South and West especially have come to realize that the modern auto cars save both time and money for them, besides being put to use in various ways upon the farm. It is no longer a luxury, but a necessity, and consequently all who can possibly afford it are investing in machines. An Agricultural Motor Competition THERE will be an agricultural motor competitien at the Canadian Industrial Exhibition, which is to be held in Winnipeg, Canada, from July 5th to July 22nd, 1911, and which will be open to the world. The .engineers in charge will be Prof. A. R. Greig and L. J. Smith. Paris Exposition THERE is some talk of having an exposition at Paris in 1920. The senatorial commerce and industry committee lately voted in favor of the project. It is intended to bring the matter before the Minister of Commerce and to have Parliament take some action thereupon. However, it is not at all certain that the project will be carried through, as there considerable opposition to it.