by WILLIAM H. TELLER, Cadastral Engineer, Denver, Colorado, BLM

ANY of the basic principles of surveying date all the way back to the early Egyptians. Though the specific methods and equipment the Egyptians used have not survived, we do know their measurements were remarkably precise.

The Great Pyramid of Gizeh (Khufu), for example, is laid out with its base oriented to the four points of the compass. The base of the pyramid was so accurately measured that the four sides (9,068.8 inches) have an average error of only 10 inch in length and 12 seconds in angle from a perfect square. The pyramid was built about 4700 B. C.!

The Egyptians were also very much concerned with the survey of property boundaries for taxing purposes-a job that had to be done many times over in the wake of the annual floods in the Nile Valley.

The job of accurately determining the distance between two points on the surface of the earth has occupied the time and talents of countless generations of surveyors.

Though many advances have been made over the years in the methods and equipment for measuring angles and determining direction-the astrolabe, the marine compass, Vernier scale, sextant and transit, and theodolite-the methods for measuring distances have changed much more slowly.

Historically, distances have been using some known standard lengtha man's stride, the distance a man rope, a chain, or a tape, and so f cient times a rope was used. It wa in water, dried, and then coated heav to insure constant length.

The most significant advance in th and accurate measurement of dista from the very recent development measuring devices. These are larg growth of radio and radar develo fected during World War II.

Several electronic measuring instr been invented and are now in use. instruments operate on the principle ing the actual distance between p earth's surface by measuring the tim impulse of some sort

as a rac

travel from one pointher and

This is like solving the familia problem: if a man walks from his store at 3 miles per hour, and it take to make the round trip, how far away

Several media have been used for These vary from the measurement of tween the creation of a sound and rec echo, to the modern measurement of t between the transmission of an elect or a beam of light and the reception or reflected wave. By using very a suring devices the actual interval points can be precisely determined.

Equipment of this type has now b by the Bureau of Land Managen cadastral surveys on public lands-la familiar checkerboard of townships as the necessary forerunner to effecti for the conservation and developmen lic lands and resources.

When the Bureau was studying electronic measuring equipment for land surveys, three requirements ha The equipment had to be durable, dep portable-all in about equal measure. that seems to fill the bill is now being The electronic measuring system i

Bureau is a device very much like the directional and distance measuring radar equipment used by the Military Services. It comes in two basic parts the master unit (which sends out the electronic signal) and the remote unit (which receives the signal and sends it back to the master unit).

Electronic pulses are generated and broadcast at the master unit, received at the remote unit, and then re-broadcast back to the master unit. The signal received at the master unit is made visible on a small cathode ray tube (a cousin of the big tube in a television set) upon the face of which is marked a circular scale. The impulses are read by means of a fine illuminated circle which appears on the face of the tube, the circumference of which is interrupted by a small break, called a "blip."

In addition to the face of the cathode ray tube, certain other controls are located on the instrument cabinet. AH reading and recording is done at the master unit. The remote unit only serves as a receiving and re-broadcasting station.

By characteristics of the signal being generated at the master unit (including the speed at which the wave travels) it is possible to measure the distance between the master unit and the remote unit by calculating the time it takes the electronic signal to go from the master unit out to the remote unit and back again. Different time is measured by comparing the "phase" characteristics of the wave as it is transmitted and received.

know in advance all of the electronic

The system operates on very high frequencies and the time interval is measured in very small units called millimicroseconds (0.000000001 seconds) a very small interval of time, and one that would be much too small to measure except by electronics.

Readings are taken at several different frequencies in order to minimize certain errors. The time intervals are then multiplied by the speed of the transmitted beam (approximately 186,000 miles per second) and divided by 2 to obtain the actual distance between the two units. Some slight corrections are then made to take into account daily changes in the moisture content of the air, air pressure, and other weather conditions. The calculations are very simple and can be done right on the spot in a very few minutes.

The job of measuring the distance between two points ordinarily takes less than 30 minutes at each station. One of the remarkable characteristics of this electronic equipment is the fact that it can accurately measure 10, 20, or even 30 miles or more with a probable error of only about 3 parts per million, plus or minus 2 inches.

The instruments are set up on their tripods at the stations between which the distance is to be measured. The power supplies are connected and the instruments are warmed up to operating temperature. This usually takes about 10 minutes. After the warm-up period the units are oriented toward each other. If the points are close, so that

A booklet "Information Relativ and Disposal of Public Lands and Alaska," Information Bulletin No. by the Bureau of Land Managemen for 20 cents a copy from the Supe Documents, U. S. Government Pr Washington 25, D. C.

TWO NEW OFFICES

In order to provide better services and meet the growing demands for and resources, BLM has established offices.

A district forestry office is no Ukiah, California, at 307 N. Main S A district grazing office has be Bridger, Mont., serving public la Montana counties.

ON THE BOOKSHELF

The Federal Lands: their use and by Marion Clawson and Burnell more: Johns Hopkins Press, 1957 Dr. Clawson is former Director of t Land Management.

American Agriculture: Geography Conservation, by Edward Higbee John Wiley & Sons, 1958), 399 pages.

Beginnings of American Rectangul vey System, 1784-1800, by William D

doctoral dissertation at the University of Chicago, from whom copies are available.

Timber Resources for America's Future, Forest Report No. 14, Forest Service, U. S. Department of Agriculture, January 1958. 713 pages. Copies are available from the Superintendent of Documents, U. S. Government Printing Office, Washington 25, D. C. at $7.

LEGISLATION PROPOSED

Legislation to prevent the subdividing of Federal oil and gas leaseholds into leases covering less than 640 acres has been urged by the Department of the Interior, Secretary Fred A. Seaton announced.

He said the proposed minimums would protect unwary investors against misleading advertising promotions which imply that many average citizens can "strike it rich" by speculating in a subdivided lease covering a small holding, usually 40

acres.

The legislative safeguards were requested in a letter to Speaker Rayburn of the House of Representatives. Certain exceptions to the 640-acre minimum would be provided. "One necessary exception would be where the entire acreage of an existing valid lease is less than 640 acres," the report said. "Other exceptions would be where there is evidence that exploration or development will actually be undertaken in the assigned area."

"In past years many persons advertising in newspapers and periodicals throughout the Nation have offered for sale to the public 40-acre oil and gas leases issued by the Government," the legislative report said. "The customary price for the sale of such a lease is $100. In their advertising these persons have implied that many can be lucky enough to 'strike it rich', relying solely on the information offered.

"In their advertisements such psychologically encouraging items are employed as maps which show oil activities within the particular State. Generally speaking, the prospective customer cannot distinguish between development and wildcat drilling.

"In reality, the profitable leasing of lands for oil and gas cannot be based simply on such information but must, rather, be the result of the use of technical skill and science and by the investment of considerable sums of capital.

"The average layman, inexperienced in the oil industry and ignorant of the time and effort needed in the selection of drilling sites, can be easily misled by advertisements which report oil strikes."

The report charged that such advertisements caused an unprecedented, tremendous influx of oil and gas lease offers for 40-acre tracts and imposed a heavy burden on the various land offices. In 1952 steps were taken to restrict issuance of oil

and gas leases of less than 640 acres. But advertisers were still permitted to subdivide their larger leases and assign or sublease 40-acre tracts.

The report called for an amendment to the Mineral Leasing Act of 1920 so that the Secretary of the Interior, under most circumstances, would be prohibited from approving any such assignment offer covering less than 640 acres.

CHANGES IN MINERAL LEASING
REGULATIONS PROPOSED

Secretary of the Interior Fred A. Seaton has announced proposed amendments to the Federal oil and gas leasing regulations which would spell out in greater detail the Government's procedures and requirements in connection with the acreage limitation provisions of the Mineral Leasing Act.

Under the mineral leasing law no person or company may hold more than 46,080 acres in Federal oil and gas leases in any one State or more than 100,000 acres in Alaska.

Under the proposed changes in the regulations, acreage in applications or offers for oil and gas leases would be included in calculations of acreage held and subject to the limitations. Though this is not a new practice, it is now being specifically spelled out in the regulations. The acreage limitations have been construed consistently to apply to lease applications and offers as well as to leases almost since the enactment of the Mineral Leasing Act, Secretary Seaton said.

Applications and offers for leases committed to a unit or cooperative plan and included in an operating, drilling, or development contract approved by the Secretary of the Interior would continue to be excluded in counting up the accountable acreage of lease holders.

The proposed amendments to the regulations also provide that the Bureau of Land Management may require anyone applying for a lease to file a sworn statement showing his complete lease holdings including any leases which he may not himself own but in which he may have a partial or indirect interest. Lease applicants (offerors) will thereby be subject to the same requirements as may now be made of lessees and lease operators. If anyone exceeds the acreage limitation the last lease or leases acquired by him which create the excess acreage holding may be canceled, or he may be compelled to dispose of them.

The proposed changes in the oil and gas regulations also provide that anyone submitting a lease offer must furnish the Bureau of Land Management a signed statement that he is the sole party in interest in the offer and any lease which may result from it. If he is not the sole party in interest, he must give the complete details about other interested parties including the nature and extent of any oral or written agreement between (Continued on page 15)

ABANDONED HORSES (Continued from page 3)

ample authority to prohibit such practices, but if they do take place they have occurred without the knowledge of the authorities. Inhumane treatment of any animal is not tolerated by officials of the Bureau or by any other Government agency. The real cruelty is the slaughter by predators of unclaimed animals that have been turned out on the range. These predators take their toll when the horses are too weak from starvation to protect themselves.

Many animal lovers, in the belief that the wild mustang still exists but is rapidly disappearing from the Western range lands, have urged the creation by the Federal Government of a wild horse refuge. There are already a number of wildlife refuges and game ranges in the West and a few unclaimed horses are reported to be found on them from time to time. But here, as well as on the public range, they present a management problem because of their competition with other forms of wildlife and domestic stock.

It is extremely doubtful that the creation of a refuge for abandoned horses would be practical because they are constantly moving long distances in search of food and forage and it would be difficult to confine them to a restricted area. The Bureau estimates that there are approximately 15,000 to 20,000 abandoned horses still on Western range lands. Should it ever develop that they are actually facing extinction it seems certain that some form of public protection will be given them.

While the total horse population has decreased materially with the general use of tractors, the popularity of light horses is emphasized by the fact that today there are 13 times as many as there were in 1918, one of the reasons being the large number of saddle horse clubs. Also, it is estimated that there are 500,000 cow ponies on Western ranches, a number which will remain constant, since no substitute has been found for the cow pony in handling range livestock.

According to the U. S. Department of Agriculture, the total horse population (including mules) in the United States in 1957 was estimated at about 32 million head. This number has been declining for many years, but may be levelling off. By comparison, there were an estimated 23 million horses and mules in the United States in 1910.

CORNFIELD WASH (Continued from page 5)

Survey six years ago, specific information is now being obtained on runoff and sediment movement in the Cornfield Wash area. Accurate hydrological information is exceedingly valuable in determining basic designs for the construction of detention dams. A storage factor of one-half acre foot of sediment per square mile of drainage area per year has been found inadequate. Up to three acre feet of sediment per square mile of drainage area per year have been recorded by the Geological Survey in Cornfield Wash. Sediment now occupies approximately one-half of the storage capacity of the eighteen Bureau structures in Cornfield Wash. Ways and means to extend the life of these structures is a serious problem demanding and receiving attention.

Holding soil in place by an improved vegetal cover will retard the sediment deposition rate. There is an added need, however, to achieve sediments deposition in the gullies themselves before lodgment in the storage areas of the detention dams. Such deposition would not only lengthen the life of the dams but also would contribute materially to the process of reestablishing the original valley floors.

One method used to achieve restoration of valley land and to protect earthwork structures has been the construction of woven wire check dams across the low places in the valley (swales) above the storage basins. These wire checks extend to grade on either side and are not over two feet high at the low points of the swales. Being level across the top, they serve as weirs and widen the flood flows, thus reducing cutting by the overpour. Vegetal material from the watershed collects against the wire checks; flow velocity through the wire mesh is reduced; and sediment settles out. Gradually, the gully begins to regrade upstream from the wire checks.

As the gully regrades upstream, the water table rises and moisture is available to the relatively shallow rooted forage grasses. Weeds and other annuals are first to become established. As organic matter and soil deposition increases, grasses come in. Restoration thus has begun and the treated areas become increasingly productive. In the beginning, the recovered acreage is small. One important aspect, however, is that the range user can see the improvement and begin to graze the land again.

Small earth diversions are constructed across and beside gullies. These are used primarily where large flows are controlled by detention dams upstream. The result is that soil accumulated from sheet erosion and bank sloughing remains in place where more moisture is retained and is available for plant growth. Here again weeds and forbs come in first, then grasses return and production is increased. Fencing is necessary to