An on-line tree has further information about the sons mentioned in the Will - Thomas Ernest DOBSON 1870–1933 and Robert Mackenzie Daniel DOBSON 1873–1939. There was also a son William DOBSON 1868-1886 whose death was apparently caused by a fall from a horse - he was a jockey or horse trainer.
I have not verified these dates on indexes so you would need to check them; however all of the information is from cited sources.
Judith