On the left we passed Netley Abbey, a very pretty, small ruin, and near it a large military hospital and college, where medical officers of the army study the complaints of the troops who have been in tropical climates.  On the opposite side, at the end of a point stretching partly across the mouth of the water, we saw the old grey, round castle of Calshot, which was built to defend the entrance, but would be of little use in stopping even an enemy's gunboat at the present day.  However, papa said there are very strong fortifications at both ends of the Solent, as the channel here is called.  No enemy's gunboat could ever get through, much less an enemy's fleet; at any rate, if they did, he hoped they would never get out again.