ACCURACY OF MODELS

The models used in my experiments accounted for in 1973 and 1980 were produced by sculpting a particular species in plastic material and then raising it to its appropriate specific weight by copper-plating (Reyment and Eckstrand 1957). Needless to say, the success of such an enterprise depends greatly on the skill and learning of the technician charged with the task. This work was undertaken by a professional sculptor, Mr. Eric Ståhl, and for the second part of the work, requiring special facility in working with plastics, by Mr. Bertil Annell. An idea of the accuracy of our modelling technique may be gained from Figure 5 where an original shell of Nautilus pompilius is shown together with a model. It will be seen that the floating capabilities of both are nigh on identical.

The models were made from actual specimens as follows. The shells were dissected and the component parts for the models constructed by means of a commercial vacuum-moulding machine. This technique proceeds by quickly sucking a preheated sheet of plastic of suitable thickness around a mould. Vacuum-moulding is a widely used method for manufacturing toys.