A pair of small hot air engines, one of freelance design fitted with a propellor - it turns over freely with compression and attempts to run when heat is applied. Dimensions 4 1/2 x 5 x 7 1/2 inches L x W x H.
The other is based on a Robinson, complete and turns over freely, dimensions 5 x 4 x 5 1/2 inches L x W x H.