Queequeg views the squid they past a while ago as a good omen.  He believes that it indicates that there is a sperm whale nearby.  Soon enough, they spot a whale and Stubb and Tashtego kill it successfully.  Then, Ishmaes describes a quick account of harpooning a whale.  He says that it is a very difficult process.  This is because the harpooner has to row strenuously before shooting the whale and is then breathing to heavily to aim properly.