Instructions for the construction of the following apparatus for the secondary school science laboratory are included in this issue of the Scottish Schools Science Equipment Research Centre Bulletin: a cheap water purifier using an expendable deionizer can; a simple amplifier suitable for detecting or displaying D. C. currents of 1 microamp or less on meters requiring up to 10 milliamp for operation; a silicon diode thermometer; and a simple live-trap for small mammals. Circuit details are given for the electronic apparatus. Suggestions for the use of the thermometer in biology investigations are included. A series of short announcements of meetings and apparatus suppliers directed at Scottish readers is included. (AL)