At last things came to such a pass that whenever he felt like taking a littleexercise，or had a few minutes of spare time，or even happened to think of it，Bingo would sally forth at racing speed over the plain and a few minutes later return，driving the unhappy yellow cow at full gallop before him.
At first this did not seem very bad，as it kept the cow from straying too far;but soon it was seen that it hindered her feeding.She became thin and gave less milk;it seemed to weigh on her mind too，as she was always watching nervously for that hateful dog，and in the mornings would hang around the stable as though afraid to venture off and subject herself at once to an onset.
This was going too far.All attempts to make Bingo more moderate in his pleasure were failures，so he was compelled to give it up altogether.After this，though he dared not bring her home，he continued to show his interest by lying at her stable door while she was being milked.
As the summer came on the mosquitoes became a dreadful plague，and the consequent vicious switching of Dunne’s tail at milking-time was even more annoying than the mosquitoes.
Fred，the brother who did the milking，was of an inventive as well as an impatient turn of mind，and he devised a simple plan to stop the switching.He fastened a brick to the cow’s tail，then set blithely about his work assured of unusual comfort while the rest of us looked on in doubt.Suddenly through the mist of mosquitoes came a dull whack and an outburst of“language”。The cow went on placidly chewing till Fred got on his feet and furiously attacked her with the milking-stool.It was bad enough to be whacked on the ear with a brick by a stupid old cow，but the uproarious enjoyment andridicule of the bystanders made it unendurable.
Bingo，hearing the uproar，and divining that he was needed，rushed in and attacked Dunne on the other side.Before the affair quieted down the milk was spilt，the pail and stool were broken，and the cow and the dog severely beaten.