SummaryA semi‐automatic apparatus is described for measuring the capacity of milk bottles filled to a prescribed level. The bottle is filled from a large calibrated burette with coarse and fine deliveries. When the water reaches the filling level the flow is stopped by an electromagnetic clamp actuated by a Burndept Proximity Switch, whose probe, mounted in the bottle neck, is sensitive to very small capacity changes caused by movement of the water level. The apparatus is designed for quick and simple operation with large numbers of bottles and gives results of good accuracy and precisio