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Radiosonde: A battery-powered telemetry instrument carried into the atmosphere usually by a weather balloon that measures various atmospheric parameters and transmits them by radio to a ground receiver. Modern radiosondes measure or calculate the following variables: altitude, pressure, temperature, relative humidity, wind (both wind speed and wind direction), cosmic ray readings at high altitude and geographical position (latitude/longitude). Although modern remote sensing by satellites, aircraft and ground sensors is an increasing source of atmospheric data, none of these systems can match the vertical resolution (30 m or less) and altitude coverage (30 km) of radiosonde observations, so they remain essential to modern meteorology.

A rubber or latex balloon filled with either helium or hydrogen lifts the device up through the atmosphere. The maximum altitude to which the balloon ascends is determined by the diameter and thickness of the balloon. Balloon sizes can range from 100 to 3,000 g. As the balloon ascends through the atmosphere, the pressure decreases, causing the balloon to expand. Eventually, the balloon will expand to the extent that its skin will break, terminating the ascent. An 800 g balloon will burst at about 21 km. After bursting, a small parachute on the radiosonde's support line may slow its descent to Earth, while some rely on the aerodynamic drag of the shredded remains of the balloon, and the very light weight of the package itself. A typical radiosonde flight lasts 60 to 90 minutes.

The modern radiosonde communicates via radio with a computer that stores all the variables in real time. The first radiosondes were observed from the ground with a theodolite, and gave only a wind estimation by the position. Modern radiosondes can use a variety of mechanisms for determining wind speed and direction, such as a radio direction finder or GPS. The weight of a radiosonde is typically 250gm.

Reference Library I: A collection equivalent to an encyclopedia. Also issued as a set of 5-20 books. Weight: 2kg (discs); 5-10kg (books).

Research Library II: A collection of computer disks giving a in-depth knowledge of a specific subject. Also issued as sets of 20-50 books. Weight: 2kg (disks); 15-25kg (books).

Slide Rule: A mechanical analog computer, which is used primarily for multiplication and division, and for functions such as exponents, roots, logarithms, and trigonometry. It is not typically designed for addition or subtraction, which is usually performed using other methods. Maximum accuracy for standard linear slide rules is about three decimal significant digits, while scientific notation is used to keep track of the order of magnitude of results.

Slide rules exist in a diverse range of styles and generally appear in a linear, circular or cylindrical form, with slide rule scales inscribed with standardized graduated markings. Slide rules manufactured for specialized fields such as aviation or finance typically feature additional scales that aid in specialized calculations particular to those fields.

The slide rule is closely related to nomograms used for application-specific computations. Though similar in name and appearance to a standard ruler, the slide rule is not meant to be used for measuring length or drawing straight lines.

At its simplest, each number to be multiplied is represented by a length on a pair of parallel rulers that can slide past each other. As the rulers each have a logarithmic scale, it is possible to align them to read the sum of the numbers' logarithms, and hence calculate the product of the two numbers. Weight: 0.05kg.