The general large-scale circulation of the global atmosphere has its basic driving mechanism in the equator-poleward temperature gradients in both hemispheres. It has become increasingly obvious over the last few decades that to understand and predict the behaviour of the atmosphere at any point, it is essential to understand the behaviour of the total global fluid system. The Global Atmospheric Research Project (GARP) is an outcome of this recognition. Studies of the heat sinks (the polar regions) are therefore just as important as studies of the heat source (the equatorial regions) to understand the meteorology of the planet. Interest in polar meteorology has undergone many cyclic fluctuations, peaking during the various international polar years and, more recently, during the International Geophysical Year, 1957–58. At the present, the focus of GARP's first objective (improved extended weather forecasts) is on the tropical heat source, where convection and cloud formation and dissipation are still relatively little understood processes. However, the second GARP objective (better understanding of the physical basis of climate) requires more attention to be devoted to the cryosphere, its long-term interaction with oceans and atmosphere, and its role as an indicator of climatic change. The idea of a polar experiment (POLEX) was initially introduced by Treshnikov and others (1968) and by Borisenkov and Treshnikov (1971). A summary of the early history of POLEX was recently given by Weller and Bierly (1973). The two closely related objectives of POLEX that most directly pertain to GARP may be restated in their simplest terms as (1) a better understanding of energy transfer processes and the heat budgets of the polar regions for the purpose of parameterizing them properly in general circulation models and climate models, and (2) provision of adequate data from the polar regions during the First GARP Global Experiment (FGGE) in 1978.

A geodetic survey by shoran trilateration, to approximately second-order accuracy, of the islands of the Canadian Arctic archipelago was completed in 1957. This was the culmination of a programme started in the south-central section of the country in 1949.

Shoran (short-range aid to navigation) was developed during World War II as a navigational aid for precise tactical bombing. It consists of two radar transponders at known points on the ground and another radar unit in an aircraft capable of measuring the time required for radio waves to travel from the aircraft to each ground station and to return. These times are converted to distances by an intricate electro-mechanical system and the distances are shown on counters, reading to 0·001 mile. For the military application the distance between transponders was known and the position of the aircraft could be plotted from the mileage-counter distances; for geodetic application the mileage-counter distances are used to measure the distance between the two transponders.

Aviation is playing an increasingly important role in developing the resource potential of northern Canada. It is the most common means of supplying the oil rigs on Melville Island, the mining camps in the Mackenzie Mountains, and the meteorological stations on the pack ice. New technology has increased both capability and capacity. Pipe and drilling equipment can now be flown non-stop from southern Canada to airfields on the Queen Elizabeth Islands; helicopters able to carry two tons then distribute the equipment to well sites. Very rapid and precise land surveying can be conducted using the Bell Jet Ranger helicopter. Recently, a 16 640 km2 region of northern Alberta was surveyed in less than five days.

By a Grace, dated 26 November 1920, the Senate of the University of Cambridge approved an earlier recommendation of the Council of the Senate “That the University would welcome the establishment of the proposed Polar Research Institute at Cambridge.…” Frank Debenham's “Retrospect”, written to mark the twenty-fifth anniversary of this date, told of the circumstances that led to the formation of the Institute, and of its aims and facilities. Now, to mark the fiftieth anniversary of that date, a brief note seems appropriate.