The following is a private letter from a lady of Springfield, Mass., who was a passenger on board the steamer Theo. D. Wagner, lately burnt at sea.

My Dear ---------; We live to to thank God for His goodness and for His Excellent kindness, though the Theo. D. Wagner has gone in ashes to the bottom of the sea, and has taken with it our accumulated treasure of a life-time.

On Saturday, at 5 P.M. a dense smoke was seen to issue from around the smoke-pipe, and the alarm of fire created universal panic . Most of the ladies, in spite of the remonstrances of the officers, worked at one of the pumps and assisted in passing buckets of water. The fire gained rapid headway, and we were unable to get to the state rooms for life-preservers. We were absolutely calm, though we had no hope of preservation. Two sails, eight or ten miles ahead, seemed wings of primse, but the man at the wheel said: "They can see the fire, but this dead calm will keep them from us; we must try to hold together till we can get to them."

Soon after 6 o'clock they were within hailing distance, and we heard from both brig and schooner a hearty "Aye, aye, Sir," in response to the Captain's cry of "We are all afire; will you lay by and lend us a helping hand, and be ready to take our passengers, if we must leave the ship?"

At 6:30 o'clock we were ordered to take to the small boats, unburdened with the smallest parcels. We felt richer then in the sweet promise of life; but I can but wih that the nutshell, which can hold all my present material possessions, was lost, and my three colossal trunks, which I shall see no more, were in its place.

I walked the deck of the brigantine all the night long, not closing my eyes until 9 o'clock on Sunday morning--unwilling to take them from the majestic spectacle of our burning ship. I wanted BRADFORD to share the watch with me. Two days before, I looked with awe on the grand truth-telling picture of the "Sealers Crushed by Ice." This will be a picture in my memory foreer, I said to him, when I turned from it to go to our steamboat. Now my life has given me a pciture--all my own--solemn and grand enough to keep that company.

This is the close of our second day on the Brigantine, and hope to reach New-York at 10 to-night. We are weak and worn--exhausted first by incessant sea sickness during our two days on the Wagner, and feel now great pain and prostration from our heavy work.

As I stood with the two captains watching the fire when the morning was breaking, and lsitening to their mutual talk of life on teh sea, I was struck with their expressions of awe and horror. A timid woman's lips would have trembled no more than his (the captain's) did when he said, with his eyes on the flames, "Oh, a dreadful thing is a fire at sea!"

At 6 P.M. we spied a steamer southward bound. Our flag of distress was hoisted, and our hearts leaped with confident anticipations of being helped on our way; but the steamer passed us by, drawing near the burning wreck, but passing on without looking for floating lifeboats. We felt less regret when we saw them sail on than we should have done if we had been dependent on their mercy.

In peace and satisfaction we send you this greeting. Yours, truly,

LUCY CHASE

AT SEA. Oct. 22, 1866