A Simple and Inexpensive Apparatus for Photographing Events at Pre-set Intervals

Extract

During studies of the locomotory behaviour of blowfly adults, one of us G.W.G.) developed a simple tilting-type actograph wherein an electrical circuit was opened or closed each time a fly moved from one end of a small cage to the other. Circuits from six such cages were connected to solenoid-activated pens on an event recorder so that movements in each case were recorded as crosslines on the respective pen records. At peak activity, an individual fly may activate a pen up to 4,800 times during a 24-hour period. With six flies active at the same time, abstraction of a day's chart was a formidable and time consuming task. In analysing the data, activity counts over consecutive half-hour periods proved adequate, and some method was sought whereby half-hour activity records could be obtained. Six electrically operated counters were arranged so that they were activated by the closing of contacts attached to their corresponding pens. Thus, each time an actograph circuit was closed, a pen was activated producing a crossline on the chart, and a count of fly activity was registered by a corresponding counter. To simplify the situation further, some method of automatically photographing the counter dials at half-hour intervals was required. The photographic apparatus subsequently developed proved to be simple, inexpensive, and reliable. Because it is adaptable for use in many situations requiring photographic records at pre-set intervals, details of its construction arc reported herein.