and other departments of the Government 29 channels, making a total of 639 two-tenths of 1 per cent channels. Here is the point I was trying to bring out before: Since you have all the browns or all the point-to-point services in one block, you might be able to do much better by way of separation than if you had the brown mixed up with the red, for example. Aviation can not at the present time have a separation better than two-tenths of 1 per cent. I think it would be impractical to require them to go to one-tenth of 1 per cent separation. If all are mixed up together, you would have a difficult time; you would have to hold back the development of point to point for aviation. Senator DILL. How do you accommodate 15,000 or 16,000 amateurs in this block? Lieutenant Commander CRAVEN. They have interfered with each other. That is a problem for the amateurs, and they may lead us again into something new; they may be able to take 15,000 amateurs and use this comparatively small block of frequencies and find a way to carry on communication without interference. That is their problem. And if you are not optimistic, it almost looks impossible. Senator DILL. How wide a separation is there in the amateur channels? Lieutenant Commander CRAVEN. In the Federal Radio Commission we let the amateurs almost govern themselves. They stay within the whole band; they are using something in that band, and they almost govern themselves. Senator DILL. They are not required to keep on any particular wave length? Lieutenant Commander CRAVEN. No, sir; so long as they do not go outside of their band. But there are certain technical restrictions on them. Senator DILL. Do they complain of one another? Lieutenant Commander CRAVEN. They probably have their own family fights. Senator DILL. But I wondered if they complain to the Federal Radio Commission. Lieutenant Commander CRAVEN. No; I think they govern themselves pretty well. They have an organization of their own called the Amateur Radio Relay League. Senator DILL. Yes, I know that, and we hope to have Mr. Maxim here before us. Lieutenant Commander CRAVEN. This band is also what we call the continental short-wave band, or continental high-frequency band. Certain waves in the lower part of the spectrum are not expected to carry so far in the daytime, they do not go very far then, but at night they go up to a distance of 1,000 miles in the higher part of the band. In this part, in here on the chart, from 4,000 kilocycles on up, in the daytime they only go, regardless of power, in the neighborhood of less than 1,500 miles, but at night they may go round the world. Senator HOWELL. That is shown by reason of the fact that amateurs have communicated with Commander Byrd at the South Pole. Lieutenant Commander CRAVEN. Yes, sir. Those waves may be carried around the world. The International Conference at Washington in 1927 took 6,000 kilocycles as the arbitrary dividing line d tel between short and long distance communication. As yet the nations of the world have not settled the problems of interference in this band between 4,000 and 6,000 kilocycles. There is still something to be done there. On the basis of that we have this allocation here as shown on the chart to the various types of services, as arranged with the North American nations. We still have to find some means of avoiding interference at nighttime with European nations. So we can not say now just what the value of a channel may be in the United States. Senator HOWELL. Six thousand kilocycles is about what wave length? Lieutenant Commander CRAVEN. Fifty meters. Senator HOWELL. How much higher can you go effectively with short waves? Lieutenant Commander CRAVEN. We can go at the present time to at least 23,000 kilocycles, and the art is now being developed on up to 30,000 or 35,000 kilocycles. Senator BARKLEY. Are these waves carried a uniform distance from the earth? Lieutenant Commander CRAVEN. They are reflected back around the surface of the earth. Senator BARKLEY. But are they always the same distance from the surface of the earth in the case of any wave? Lieutenant Commander CRAVEN. All waves are reflected back by this Heaviside layer, which goes up or down according to the time of day or year; they always hit that layer at about the same height at any particular time. Senator BROOKHART. Is this Heaviside layer at an even distance from the surface of the earth or from the center of the earth? Lieutenant Commander CRAVEN. From the surface of the earth, so that night or day it is at about a definite height. Senator BROOKHART. It is the surface of the earth that regulates it and not the center of the earth? Lieutenant Commander CRAVEN. I believe so, but, Senator Brookhart, you understand that we do not really know much about that. Senator BROOKHART. That is mostly theory. Lieutenant Commander CRAVEN. Yes, sir; it is just a theory. Senator WAGNER. What happens to a wave that breaks through the Heaviside layer? Lieutenant Commander CRAVEN. That is the question that brings up the possibility of communication with Mars. Senator PINE. The low frequency waves have been assigned to international use. Lieutenant Commander CRAVEN. The very low frequency waves; yes, sir. Senator PINE. And the very high frequency waves have been assigned to national use? Lieutenant Commander CRAVEN. The wording of the International Convention relative to high frequencies is one of great liberality. They say not much about it, but I will read it: It is recognized that short waves (frequencies from 6,000 to 23,000 kilocycles approximately-wave lengths from 50 to 13 meters approximately) are very effieient for long-distance communications. It is recommended that as a general rule this band of waves be reserved for this purpose in services between fixed points. Also they state: In the case of a fixed short-wave station intended to carry on regular service and the radiation of which would be likely to cause international interference, the administration concerned must, as a general rule, before the completion of the station, and in any case before it is open for service, notify to the International Bureau the frequency assigned to that station. And it further says: Such notification, however, shall be sent only when the administration concerned shall have ascertained that the service in question can be established within a reasonable time. Senator PINE. Are we making the best use of long waves when we assign them to international use? Lieutenant Commander CRAVEN. The very long waves? Lieutenant Commander CRAVEN. That is the only use that you can assign them to in order to make them practicable. The CHAIRMAN. You may proceed. Lieutenant Commander CRAVEN. These particular waves that I mentioned before, we hoped to use on this continent, all of them, regardless of what they do in Europe. That matter will still have to be settled as to questions of interference. We have a tentative arrangement with Canada and Mexico-but Mexico was not a party to it and Cuba, by which certain general prior rights were given in certain of these waves. That is open to possible evolution and change; and also especially when we have a conference with Europe it may have to be changed. Senator KEAN. Will you again take up the question of the aurora borealis and explain that to us? Lieutenant Commander CRAVEN. Well, Senator, I do not know very much about it, and therefore do not know how to explain it very well. I have not made very much of a study of it, except that I believe it affects the ionization of the Heaviside layer, and in so doing affects the reflecting or refracting values of that layer, and causes all sorts of things to happen. Senator BROOKHART. In other words, just messes things up? Senator KEAN. Does this influence mess things up more in Alaska than in the United States? Lieutenant Commander CRAVEN. Well, I presume it would since the effect of the northern lights is greater there than here. But I do not know that that is so. I am getting up in the clouds too much when I talk of this matter, because I do not know much about it. The CHAIRMAN. Have you another chart to show us? Lieutenant Commander CRAVEN. Yes, sir. This is the next chart, and is from 6,000 to 23,000 kilocycles, and perhaps involves one of the most important subjects we have in the future of radio. In this band you will find the most valuable of the waves. I will explain as we go along: The first section, 6,000 to 6,640 kilocycles, in the purple, is assigned to what we call relay broadcasting. You will find some other purples throughout the spectrum, in here and in the table which I present to the committee these will all be enumerated. These waves are useful at nighttime, and here are the ones in the daytime, which are very useful, and transmit over long distances on a power of 20 kilowatts as compared to the low-frequency 200kilowatt stations. A broadcasting station can transmit their program on this wave, and have another station pick it up and retransmit it on their regular broadcasting wave. Now, the Federal Radio Commission has more or less determined or settled for the moment, that these should be for long distance relay broadcasting. There are only about 34 waves for the entire world for this service, and the world is already claiming them all, each nation wants them all. So we are going to have a very difficult problem. The United States alone could very easily use all these waves if permitted to do so. Senator WATSON. How far do they carry? Lieutenant Commander CRAVEN. The highest of these frequencies will carry round the world, and at nighttime all will carry around the world. Senator WATSON. All of the 34? Lieutenant Commander CRAVEN. Yes, sir; at nighttime. Senator HOWELL. Can not you go outside this particular band? In other words, are not waves outside sufficient? Lieutenant Commander CRAVEN. The division among the various types of service, as you see on this chart, is made by international agreement at the Washington Convention of 1927. Senator HOWELL. So that is what is limiting that particular kind of use? Lieutenant Commander CRAVEN. Yes, sir. Senator WATSON. How many of these waves do we control? Lieutenant Commander CRAVEN. At the present time we do not control any, because I believe we will have to have an international adjudication as to who is who on the ether. Senator WATSON. If we do not have any of them, then, by the same token no other nation has any of them? Lieutenant Commander CRAVEN. No other nation has them either. Senator BARKLEY. What is the difference between nighttime transmission and daytime transmission in respect to ability to circumnavigate the globe, so to speak, because half of the world is daytime all of the 24 hours. Lieutenant Commander CRAVEN. It has to do with the Heaviside layer. At nighttime the Heaviside layer is higher. Senator BARKLEY. Do you mean nighttime at the point where the transmission is undertaken? Lieutenant Commander CRAVEN. I did not quite get your question? Senator BARKLEY. You stated that these waves were a certain length in the daytime, but that in the nighttime they would go all round the world. In view of the fact that taking the world as a whole. there is no daytime and nighttime, because half of it is light all the time, so what about that? Lieutenant Commander CRAVEN. Let me explain a little further: It has to do with the start that the wave may have, the height of the Heaviside layer at the start. When I say go round the world, for effective service in transoceanic communication you should have at least three of these short waves, placed in different parts of the spectrum, because you will find, for example, take 6,000 kilocycles, and if it starts in the United States in the daytime it only goes, say, approximately less than 1,000 miles regardless of the power you put on; you can put on 100 kilowatts and it will not go any farther. It goes until it hits the Heaviside layer, and then it is reflected back quite quickly and up again, and is absorbed before it can go very far. So that wave would do you no good if you were the owner of a transoceanic station. So you must have something else. You will find that you can take a wave in the neighborhood of 15,000 kilocycles, that has the physical properties that the Lord gave it, and possibly it will go around 2,000 or 2,500 miles in the daytime, and it may skip in the nighttime about a thousand miles and go again for about 2,000 miles, and skip again and then go around 8,000 miles. Senator BARKLEY. A sort of leapfrog performance. Lieutenant Commander CRAVEN. Yes, sir; it is called skip distance. You will find in the daytime that frequencies in the neighborhood of 20,000 kilocycles are good for distances in the United States of from 3,000 to 5,000 miles. Senator BARKLEY. Is it the atmospheric condition that makes it transmissible for long distances at night, or simply lack of interference? Lieutenant Commander CRAVEN. It is nature's law apparently. It is some handicap placed on these waves by nature. The CHAIRMAN. Is there any practical operation in relay broadcasting going on now? Lieutenant Commander CRAVEN. There are certain experiments going on now. The CHAIRMAN. But there is no regular service in relaying? Lieutenant Commander CRAVEN. There is a service of retransmission between Holland and the Dutch East Indies on short waves, and a night service by one of our electrical companies, night relay service to all parts of the world as an experiment; and there have been attempts made by certain of our companies to relay to England, but the service produced as yet is not reliable enough to make it satisfactory. The CHAIRMAN. General Squier testified the other day on some experiments in relaying programs going on now, I believe. Lieutenant Commander CRAVEN. There are some plans to put in effect programs, but I do not believe that we can say yet whether they are going to be perfect. I think some developments have to be made. The CHAIRMAN. Do you think there is a future for it? Lieutenant Commander CRAVEN. Yes, sir; a great future for it, and I think it is going to bring together the nations of the world better than we have them now so far the exchange of art and news events are concerned. The CHAIRMAN. Do you think it will ever come about that these chain stations will be done away with, and they will be using relay broadcasting instead of the wires? Lieutenant Commander CRAVEN. Unless the United States has more influence on the world, I do not believe it will be done away with. This is an international rather than a national matter. Senator BROOKHART. Is there any progress being made toward getting chain stations on the same wave length? Lieutenant Commander CRAVEN. Yes, sir. That is synchroniza tion and there has been some progress on that. I think one of the |