JOHNSON'S ISLAND, Near Sandusky, Ohio, May 6, 1864.

Colonel JAMES A. HARDIE, Inspector-General, U. S. Army:

COLONEL: I have the honor to submit the following inspection report of Johnson's Island, near Sandusky, Ohio:

Commanding officer, Brigadier General H. D. Terry, U. S. Volunteers. General Terry is an intelligent, clever gentleman, but quite as fond of a social glass of whisky as of attending to the duties of his command. The grounds and barracks of the garrison and also of the prison are badly policed; the sinks are allowed to become offensive, and although the health of the post is now good, there are indications of malarial fever, which will increase with the heat of summer unless the grounds and barracks are more thoroughly cleaned. But little judgment is exercised in the management and discipline of the prison. The wood furnished the prison and also the garrison during the past winter was of the poorest quality, consisting principally of green bass, elm, and a small amount of oak. It was furnished by Mr. Johnson, proprietor of the island, who was paid a higher price than merchantable wood was worth at Sandusky. There was no contract. Johnson wanted the wood off his land, I think. Lieutenant-Colonel Pierson, of the One hundred and twenty-eighth Ohio Volunteers, who was in command at the time this wood was purchased, appears greatly interested in Johnson's affairs. Johnson was appointed sutler by General Terry upon condition that he should take a man by the name of Finnegan as a partner. I inspected the sutler's store and found only such articles for sale as are authorized by law, though I believe they smuggle whisky to the prisoners. Lieutenant-Colonel Pierson charges Finnegan with the offense. Pierson, however, for some reason is anxious to get Finnegan out of Johnson's way. The beef furnished this post is of the poorest quality and often deficient in quantity. The prisoners get most of the fore-quarters. The hospital is not in the cleanest condition, but presents a passable appearance. The clothing, food (with the exception of beef), shelter and security of prisoners, satisfactory. Post fund collected, expended, and distributed as authorized. Commissary of subsistence and treasurer of prison fund-Captain N. Ellmaker, U. S. Volunteers. Prison fund March 31, 1864, $14,005. 08; savings for April $1,891. 60, not transferred; subsistence fund due United States May 5, $11,789. 68. Treasurer of prisoners' money, Captain Samuel Truesdell, Sixty-fifth New York Volunteers. Cash on hand belonging to prisoners, $9,363. 63.

Post quartermaster-Captain L. M. Brooks, U. S. Volunteers. Due United States May 5, 1864, $34. 85; all funds and balances counted and found correct. I think there has been a disposition on the part of officers purchasing supplies for this post to be exceedingly liberal toward parties furnishing such supplies. I have no evidence of collusion, however. Purchases are not made in excess of the wants of the post. Captain Truesdell, treasurer of the prisoners' money, is an exceedingly useful, careful man in his position. The commissary of subsistence and quartermaster are competent men. No pecuniary transactions discovered between officers and sutler, or persons furnishing supplies for prisoners. The garrison, numbering 2,238 men, is passably efficient, but not under much restraint. I think one regiment of the National Guard (100-days' men) of Ohio, with a company of artillery, the whole under the command of an intelligent, active, and diligent officer, a sufficient force to guard this island and its prisoners. Number of prisoners May 6, 1864, 2,087.

I am, very respectfully, your obedient servant,

JOHN F. MARSH,

Lieutenant-Colonel Twenty-fourth Regiment Veteran Reserve Corps.