In February, 1818, Caroline spent twelve precious days with her brother, "not in idleness," she says, "but in sorrow and sadness. He is not only unwell, but low in spirits." Later he went to Bath with Lady Herschel. "The last moments before he stepped into the carriage," says the loving Caroline, "were spent in walking with me through his library and workrooms, pointing with anxious looks to every shelf and drawer, desiring me to examine all and to make memorandums of them as well as I could. He was hardly able to support himself, and his spirits were so low, that I found difficulty in commanding my voice so far as to give him the assurance he should find on his return that my time had not been misspent. "When I was left alone I found that I had no easy task to perform, for there were packets of writings to be examined which had not been looked at for the last forty years. But I did not pass a single day without working in the library as long as I could read a letter without candle-light, and taking with me papers to copy, etc., which employed me for the _best part of the night_, and thus I was enabled to give my brother a clear account of what had been done at his return." On the 4th of July, 1819, Herschel sent a note to his dear co-worker. "Lina,--There is a great comet. I want you to assist me. Come to dine and spend the day here. If you can come soon after one o'clock we shall have time to prepare maps and telescopes. I saw its situation last night,--it has a long tail." Caroline wrote on this small slip of yellow paper: "I keep this as a relic! Every line _now_ traced by the hand of my dear brother becomes a treasure to me." Every day hereafter she spent the forenoon with Sir William. On the 15th of August she went as usual and found that he was confined to his room. "I flew there immediately," she says. "As soon as he saw me, I was sent to the library to fetch one of his last papers and a plate of the forty-foot telescope. But for the universe I could not have looked twice at what I had snatched from the shelf, and when he faintly asked if the breaking up of the Milky Way was in it, I said 'Yes!' and he looked content. I cannot help remembering this circumstance, it was the last time I was sent to the library on such an occasion. That the anxious care for his papers and workroom never ended but with his life was proved by his frequent whispered inquiries if they were locked and the key safe, of which I took care to assure him that they were, and the key in Lady Herschel's hands.