The relationship between thickness and snapping strength in egg shells of the domestic fowl

Abstract

Comparable pieces of egg shell from individual eggs of the domestic fowl were filed to give different thicknesses, they were then snapped and the relationship between snapping strength (S) and the square of the thickness (T ²) was studied. For shells filed on the outside and snapped outwards or filed on the inside and snapped inwards there was a very significant relationship between S and T ². For shells filed on the inside and snapped outwards, the mammillary knobs made no contribution to strength and it was only after these had been filed off that a typical relationship between S and T ² developed. Shells filed on the outside and snapped inwards gave very variable results in relation to the removal of the first layers of shell. In some cases the removal of a thin outer layer increased the strength and in other cases it decreased it and it was only later that a steady relationship between S and T ² developed. In general the egg shells of the domestic fowl became weaker towards the inside of the shell.