From Ontario, besides the information contained in Commodore Chauncey's letters inserted below, we learn that our fleet had come to Sackets Harbor on the 7th, inst. supposed with a view of obtaining supplies. The enemy's great ship had not then sailed. A letter dated the 7th, says: --
"The enemy's ship is ready for sea, excepting that her sails are not bent, which is expected they will be by the 12th. She is a large vessel of 102 guns. Her lower deck thirty-four 32 pounds; middle deck thirty-four 24 pounders,; had twenty 62-pound carronades on her upper deck, besides other guns. It will be impossible for our fleet to withstand the enemy on the lake. Probably the first object of the enemy will be to relieve Drummond's army, which is in great want of supplies. Bread is said to be a dollar a pound with them. The enemy made an attempt to send supplies up to them by two ships, some days since, but they were driven back by Chauncey. "It is expected an attack will be made by sea and land, in a few days. The enemy is assembling his forces at Kingston for that purpose. Drummond, it is said, will lead the attack by land.
"The harbor is completely surrounded by breastworks and entrenchments, and every preparation making to give the foe a warm reception. A large additional militia force has been called out, and is repairing to the harbor with great alacrity."