Appeal by an employer and its insurance carrier from an award of disability made to claimant by the Workmen’s Compensation Board. The issues on appeal are: (1) whether claimant suffered an industrial accident; (2) whether there is substantial evidence to sustain a finding of causal relation. Claimant was employed as a carpenter’s helper in construction work at *805Buffalo, New York. However, on November 30, 1950 he spent several hours shovelling heavy snow for his employer. He testified that after performing this work he felt unusually tired and experienced a sensation akin to that felt after running a great distance. The next day he shovelled snow again and felt pain in the left side of his back under the shoulder blade. The third day he returned to his regular duties as a carpenter’s helper and suffered more intense pain. Subsequently it was concluded by a physician, after a fluoroscopic examination, that he had a spontaneous pneumothorax with a collapse of the left lung. There is medical opinion in the record to the effect that the onset of the aforesaid condition began when he was shovelling snow, and a spontaneous pneumothorax developed gradually. We cannot say as a matter of law that this evidence was too speculative to constitute substantial evidence. Its weight was for the trier of the facts — the Workmen’s Compensation Board. Award unanimously affirmed, with costs to the Workmen’s Compensation Board. Present — Foster, P. J., Bergan, Gibson, Herlihy and Reynolds, JJ.