A few days after the action of the 13th, the army received a valuable accession in the person of Col. C. F. Henningsen, who arrived at Granada in charge of arms and ordnance stores from New-York. When not more than nineteen, Col. Henningsen had commenced his military career under the Carlist leader, Zumalacarregui; and his service in Spain was well fitted to qualify him for war in Nicaragua. Although an Englishman by birth, he had spent most of his life on the continent of Europe; and after the death of Zumalacarregui he had resided for some years in Russia. Finally in 1849 he espoused the cause of Hungarian independence and came about the same time as Kossuth to the United States. A day or two after he reached Granada he was appointed brigadier-general, and charged specially with the organization of the artillery and with directing the practice with the Minié musket. Much dissatisfaction was evinced by many officers at the rank given to Henningsen; nor were efforts wanting to create prejudices against him because he was not an American. But his own worth and merits soon overcame most of these prejudices, though in the breasts of some officers jealousy lurked to the last. Walker, however, never had reason to regret the confidence he early placed in the capacity of Henningsen. The efficiency of the new brigadier-general was soon felt in the organization of two companies of artillery and of a company of sappers and miners. Full and detailed instructions for the use of the Minié musket were written by Henningsen, and practice with this arm was carried on for some days under his supervision. He had much to combat in the idleness and indifference of the officers, too many of whom valued their rank more as an excuse for indulging their ease than as an incentive to difficult and arduous duty. He was more successful in the artillery practice than with the new rifle-muskets; for among the officers of artillery were several who had much pride of profession. The skill and experience of Major Schwartz have been mentioned, and besides him, Capt. Dulaney and Lieut. Stahle deserve mention. Capt. Ferrand had courage and little else; his laziness was intolerable. Stahle was particularly useful in the practice with howitzers and cochorn-mortars. The proper carriages for the howitzers having arrived they were more fit for service than before, and the mortars, being light and easy of transportation, carried the same shell as the howitzers. The practice with the mortars was much simplified by always using the same charge, and determining the distance the projectile was to be sent entirely by the angle of elevation of the piece.