This impregnable fortress, which may defy all human efforts for its forcible reduction, is not proof against the invasion of countless small but most sanguinary creatures that, if they could audibly express their universal craving, would make an unvaried and continuous demand of blood. The mosquitoes appear early in June, and are a most persistent nuisance during the sultry months. It is no slight advantage to Great Britain and Ireland to be free from their annoyance. I suffered greatly from their envenomed bites, and although sex or age appears to be utterly disregarded in their insatiate and incessant attacks, they are reputed to accord a preference to the blood of a stranger. The slightest aperture in the curtains of my bed resulted in numerous punctures being made in the skin of my face and hands. My friend Costello slept in an uncurtained bed, and was not attacked by the mosquitoes. He told me that, after he had resided in Gibraltar for a couple of years, they ceased to annoy him. Dr. Williams described them as "the most affectionate little creatures in the world, for if you killed one, some hundreds would come to his funeral." During the months of May and June in 1861, I heard more cannon shots than ever reached my ears in the rest of my existence. The artillery were practising daily for several hours at floating targets in the bay, and the noise was certainly far from agreeable to me. In the expression of a wish for more quietude, I met no sympathy from those who had resided in Gibraltar for a year or two, and who had become accustomed to the firing, and perhaps, if I spent a few months more in the fortress my nerves would have become more obtuse. The convict depot, outside the line wall, was very near to the battery principally used for practice, and I have seen the premises occupied by the superintendent completely clouded with smoke, whilst his walls reverberated the repeated discharges of heavy cannon. He directed my attention to the domestic fowl, of which he had a considerable number, and to the poultry of various kinds having become quite accustomed and apparently reconciled to the appalling sounds, and to the fire and smoke copiously emitted in their proximity.