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N e w Radar Altimeter Proves Valuable Tests recently conducted in the tropical forests of Central America, indicate that a Canadian developed radar altimeter can be of great value to the developing countries of Africa, Asia and Latin America in surveying their forest resources. This forestry radar altimeter was developed by the Radio and Electrical Engineering Division o f the National Research Council, and it is now being manufactured by Leigh Instruments Ltd., of Carleton Place, Ontario, Ont., Canada. It has been used successfully in Canada for forest surveying by means of low-level aerial photographs, taken at altitudes of between 500 and 2,000 feet. Precise readings of altitudes above ground level are a prerequisite for extracting quantative information about a forest area from aerial photographs. For convenience, and to ensure perfect synchronization, the radar altimeter reading appears in the corner of each photo. The altimeter also appears promising for use in other fields, such as magnetometer surveys and lowaltitude topographic mapping, The outstanding feature of this altimeter is its ability to measure actual flying height above the ground without being affected, as are normal radar altimeters, by intervening vegetation. It can be easily installed in light planes or hellcopters, Tests were recently carried out in northern Guatemala, in an area of typically lush tropical rain forest. The altimeter proved largely successful in penetrating the main tree canopy, but some difficulties were encountered in penetraring the last 20 feet of short trees, palms, vines and shrubs which are characteristic of such
forests. Howeverradarexperts believethat furthermodifica"tions and adjustments can overcome most of the difficulties, and work is continuing to this end. The initial accuracy requirement for the meter was two percent of flying height or better. This was easily met in Canadian forest surveys, but in the case of solid tropical forest cover, the results fell just short, The trials also clearly indicated that large-scale aerial photography is a most promising technique for identifying tropical tree species by their characteristic crown shape, brar~ehing habits and leaf shape, which was difficult in the past, using small and medium scale photography. It is particularly effective when the technique is integrated with the radar altimeter,
NeW
Map of the Gulf
A new bathymetric map of the Gulf of Mexico has recently been released by the U.S. Geological Surve)7. Made up of three sheets, the map gives offshore depths contoured on 20 meter intervals. The eastern portion is published as a single map entitled "DeSoto Canyon to Great Bahama Bank". The western portion, entitled "Mississipi Delta to Bahia de Campeche" is published in two sheets, The entire map was prepared in cooperation with the Woods Hole Oceanographic Institution. Both portions of the map are printed on the same scale and can be mounted together. The submarine topography is shown in considarable detail off the Texas and Louisiana coasts. Elsewhere the topography is generalized, Copies can be obtained by x~criting to the U.S. Geological Survey, Washington, D.C. 20405, U.S.A. The western portion costs $1.50 per set; the eastern portion costs $1.00.
Deep Sea Servo Recorder A unique deep sea multifunction recorder utilizing the Servo principle is now available from the Benthos Company. This newly developed instrument will record with high precision three varying parameters (more on special order) for as long as 40 days of submerged operation. The Servo technique makes the unit insensitive to position or motion, thereby permitting use in a variety of sub-sea conditions. The unit is completely self-contained for easy mounring on fixed or towed sub-sea systems. Some of the sensors available as standard accessories include temperature, depth and volumetric current flow; however, any sensor in which a resistance is varied proportionally with the sensed parameter can be used. For more information contact Benthos, Inc., North Falmouth, Mass. 02556, U.S.A.
Rapid Sediment Analyzer Rapid laboratory analysis of the grain size distribution of fine gravel and sand can now be performed by a new instrument from the Benthos Company. Before the development of this device, it was necessary to analyze grain size by much slower methods such as filtering through a series of sieves and weighing the residue collected in each sieve. The Benthos Model 3410 Rapid Sediment Analyzer utilizes a technique developed at the Woods Hole Oceanographic Institution in which the difference in relative pressure between a sample settling tube and a reference is recorded as a function of time on any XY Plotter. The resulting curve can be compared with known sediment collection curves to
A215
obtain the particle size distribution of the sample under examt, nation. For more information write Benthos, Inc., North Falmouth, Mass. 02556, U.S.A.
Acoustic Telemetering Current Meter A new addition to itsfamily of acoustic telemetering instruments was announced recently by the Benthos Company. The Type 324 Telemetering Current Meter can be utilized without any of the usual inconveniences such as conductor cable, slip rings, etc., and will provide the shipboard operator with accurate data on current speed, direction and depth of the instrument. All telemetered information is contained in a simple acoustic signal transmitred from the subsurface
package and l ~ d out directly on airy graphic reeoider, Cummt speed sensing is available in either of two ranges, 0-3 knots or 0-6 knots. Current direction infoun_ ation is available to better than 3° resolution. Depth reading can be obtained in ranges of 0-500 or 0-1,000 m (other depth ranges are available). This new instrument allows acquisition of ocean current profile informarion in real time at low cost. For further information write Benthos, Inc., North Falmouth, Mass. 02556, U.S.A.
New French EarthScience Bibliography Since January 1968 the Documentation Department of the Bureau de Recherches G6ologiques et Mini6res, in Orl6ans, France, has replaced
its cards by a computer pxocessed B ~ a p h y called
"Btbliog~h~-e des Sciences de la Terre". This publication is montl~ty and c o m p o ~ of eight sections, covering the whole of Geosciences. The coverage of this bibliography is excellent (3000 references monthly). The time-lag between the primary source and publicaUon of the analysis is about two months. Annual cumulative index volumes will be processed~ Analysis of document content is made by a staff of specialists. Indexing is based on a keyword system. The file organisation which was chosen is composed of a permutation index of keywords, a geographic index, an author index and a listing of titles and references in a numeric order.
Self Contained S.T.D. Recorder
A216
The Bisset.Berman Corporation announces a new, completely self-contained under-water ~ t y and Temperature recorder Model 9060. This unit which is contained in a pressure case, Can be lowered by means of non-electrical cable, and has its own battery power supply sufficient for eight hou:s continuous operation. Salinity and temperature, as well as water depth are recorded on pressure sensitive paper by means o f a r o t a ~ plotter. C o m b e d action of the moving drum and styli, provide a graphic record. Great accuracy is ~ d for this instrument, which can be supplied suitable for water depths o f u p to 6000 meters. Special low salinity r ~ E e s are available, ~ the model 9 ~ also ideally suited to near ~ or ~ water research, its size, light ~ t and ragged construction allow of its bein8 safely used from small boats. For further information, contact: The Bisset-Berman Corporation, Marine Division, " G " Street Pier, San Diego, Calif.92101, U.S.A.
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forests. Howeverradarexperts believethat furthermodifica"tions and adjustments can overcome most of the difficulties, and work is continuing to this end. The initial accuracy requirement for the meter was two percent of flying height or better. This was easily met in Canadian forest surveys, but in the case of solid tropical forest cover, the results fell just short, The trials also clearly indicated that large-scale aerial photography is a most promising technique for identifying tropical tree species by their characteristic crown shape, brar~ehing habits and leaf shape, which was difficult in the past, using small and medium scale photography. It is particularly effective when the technique is integrated with the radar altimeter,
NeW
Map of the Gulf
A new bathymetric map of the Gulf of Mexico has recently been released by the U.S. Geological Surve)7. Made up of three sheets, the map gives offshore depths contoured on 20 meter intervals. The eastern portion is published as a single map entitled "DeSoto Canyon to Great Bahama Bank". The western portion, entitled "Mississipi Delta to Bahia de Campeche" is published in two sheets, The entire map was prepared in cooperation with the Woods Hole Oceanographic Institution. Both portions of the map are printed on the same scale and can be mounted together. The submarine topography is shown in considarable detail off the Texas and Louisiana coasts. Elsewhere the topography is generalized, Copies can be obtained by x~criting to the U.S. Geological Survey, Washington, D.C. 20405, U.S.A. The western portion costs $1.50 per set; the eastern portion costs $1.00.
Deep Sea Servo Recorder A unique deep sea multifunction recorder utilizing the Servo principle is now available from the Benthos Company. This newly developed instrument will record with high precision three varying parameters (more on special order) for as long as 40 days of submerged operation. The Servo technique makes the unit insensitive to position or motion, thereby permitting use in a variety of sub-sea conditions. The unit is completely self-contained for easy mounring on fixed or towed sub-sea systems. Some of the sensors available as standard accessories include temperature, depth and volumetric current flow; however, any sensor in which a resistance is varied proportionally with the sensed parameter can be used. For more information contact Benthos, Inc., North Falmouth, Mass. 02556, U.S.A.
Rapid Sediment Analyzer Rapid laboratory analysis of the grain size distribution of fine gravel and sand can now be performed by a new instrument from the Benthos Company. Before the development of this device, it was necessary to analyze grain size by much slower methods such as filtering through a series of sieves and weighing the residue collected in each sieve. The Benthos Model 3410 Rapid Sediment Analyzer utilizes a technique developed at the Woods Hole Oceanographic Institution in which the difference in relative pressure between a sample settling tube and a reference is recorded as a function of time on any XY Plotter. The resulting curve can be compared with known sediment collection curves to
A215
obtain the particle size distribution of the sample under examt, nation. For more information write Benthos, Inc., North Falmouth, Mass. 02556, U.S.A.
Acoustic Telemetering Current Meter A new addition to itsfamily of acoustic telemetering instruments was announced recently by the Benthos Company. The Type 324 Telemetering Current Meter can be utilized without any of the usual inconveniences such as conductor cable, slip rings, etc., and will provide the shipboard operator with accurate data on current speed, direction and depth of the instrument. All telemetered information is contained in a simple acoustic signal transmitred from the subsurface
package and l ~ d out directly on airy graphic reeoider, Cummt speed sensing is available in either of two ranges, 0-3 knots or 0-6 knots. Current direction infoun_ ation is available to better than 3° resolution. Depth reading can be obtained in ranges of 0-500 or 0-1,000 m (other depth ranges are available). This new instrument allows acquisition of ocean current profile informarion in real time at low cost. For further information write Benthos, Inc., North Falmouth, Mass. 02556, U.S.A.
New French EarthScience Bibliography Since January 1968 the Documentation Department of the Bureau de Recherches G6ologiques et Mini6res, in Orl6ans, France, has replaced
its cards by a computer pxocessed B ~ a p h y called
"Btbliog~h~-e des Sciences de la Terre". This publication is montl~ty and c o m p o ~ of eight sections, covering the whole of Geosciences. The coverage of this bibliography is excellent (3000 references monthly). The time-lag between the primary source and publicaUon of the analysis is about two months. Annual cumulative index volumes will be processed~ Analysis of document content is made by a staff of specialists. Indexing is based on a keyword system. The file organisation which was chosen is composed of a permutation index of keywords, a geographic index, an author index and a listing of titles and references in a numeric order.
Self Contained S.T.D. Recorder
A216
The Bisset.Berman Corporation announces a new, completely self-contained under-water ~ t y and Temperature recorder Model 9060. This unit which is contained in a pressure case, Can be lowered by means of non-electrical cable, and has its own battery power supply sufficient for eight hou:s continuous operation. Salinity and temperature, as well as water depth are recorded on pressure sensitive paper by means o f a r o t a ~ plotter. C o m b e d action of the moving drum and styli, provide a graphic record. Great accuracy is ~ d for this instrument, which can be supplied suitable for water depths o f u p to 6000 meters. Special low salinity r ~ E e s are available, ~ the model 9 ~ also ideally suited to near ~ or ~ water research, its size, light ~ t and ragged construction allow of its bein8 safely used from small boats. For further information, contact: The Bisset-Berman Corporation, Marine Division, " G " Street Pier, San Diego, Calif.92101, U.S.A.
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