Describes various uses for balloons in chemistry instruction, such as their use as stirring devices, gas reservoirs, sources of carbon dioxide, and as atomic models. (CS)

Presents the plans for constructing a mode 2 TOPS Projector-adaptor, which costs one-half that of a model described in an earlier article. The author uses a step-by-step approach to the project. (SA)

The design, construction, and operation of a solid state electrometer is described. The instrument used the case and meter movement from an obsolete commercial pH meter. The cost of materials, purchased in 1977 in unit quantities, was $60. (BB)

Describes the construction of a thermostat of double-oven design that can maintain a stability of two mdeg for several hours and can accomodate sealed-glass ampoules at elevated temperatures. (MLH)

Describes a temperature control system that can be used with a double-oven thermostat to provide two mdeg regulation over several hours. (MLH)

Discusses the contribution of 17th and 18th century instrument makers to the development and progress of science and the methods of teaching science. (MLH)

Discusses the accuracy of sundials and many factors which affect their ability to measure apparent local time. Provides directions for constructing a sundial, including how to make a universal dial. Includes background information regarding other types of sundials and descriptions of notable sundials. (DDR)

Presents an activity for students to construct their own two-cup balances. Suggests some alternatives for rejuvenating weak bar magnets. Describes how to remove burnt carbon deposits from glass vessels. (NB)

Introduces self-assembling, three-dimensional models (SAMs) that present the structure and behavior of water which facilitates a better understanding of the structural geometry of water. (Contains 12 references.) (YDS)

This article examines the role that field testing plays in environmental measurements now and for the future. Such issues as when field testing should be conducted, the reliability of field tests, regulatory acceptance, cost efficiency, and the use of mobile laboratories are reviewed. (LZ)

Describes a method to examine preparations of rocks in thin sections between crossed polaroids using a converted biological microscope or a homemade polariscope. (JRH)

Describes the construction and use of homemade kaleidoscopes using film canisters and microscope slides. (JRH)

Describes the working of the Adiabatic Gas Law Apparatus, a useful tool for measuring the pressure, temperature, and volume of a variety of gases undergoing compressions and expansions. Describes the adaptation of this apparatus to perform isothermal measurements and discusses the theory behind the adiabatic and isothermal processes. (JRH)

Describes how teachers and students can construct a mass, spring scale, lever, and pulley. (ZWH)

Describes a simple and inexpensive procedure for constructing a circuit element that will allow for continuously variable and precisely controllable low direct-current voltages. (WRM)