In Bond’s story “A Face in the Dark” the boy’s ‘strange soundless weeping’ sitting on a rock all alone that night might well suggest the unhappiness of the students of the English public school where Mr. Oliver teaches. Being a very reputed school, it forces strict discipline upon the students and they probably don’t get space to breathe. The pressure of studies adds more weight. That discontent is probably conveyed through the sobbing of the boy in the dark.
 
But to go with the main flow of the plot, the boy’s ‘silent sobbing’ is an integral part of creating an atmosphere of suspense and mystery as the author wants to give the readers a thrill with the use of carefully chosen words like ‘strange’, ‘soundless’ and ‘silent’.