Rugg, C. J.

This is a petition for a writ of mandamus. It was heard.by a single justice,* who refused to issue the writ so far as it rested in his discretion, and reported the case.

Mandamus is not a writ of right, and it is granted only in the exercise of sound judicial discretion. Hill v. County Commissioners, 4 Gray, 414. Murray v. Stevens, 110 Mass. 95. McCarthy v. Street Commissioners, 188 Mass. 338, 340. The facts are that the city council of Boston appropriated in May, 1911, $300,000 to be expended by the department of public works for the purchase of gas lamps and other apparatus for street illumination, and this amount of money is now available for that use. The respondent as commissioner of public works has refused to make the purchases authorized in this order. He was at the time of the passage of the order conducting independent investigations as to the most practical and economical system of municipal lighting, and is of opinion that, because of the initial cost and maintenance expense of the equipment for illumination by gas and the necessity for a large investment by the city, the most practical and economical system of municipal lighting is by electricity. It is not *354necessary to state at length his reasons, but they may be summarized by saying that both on grounds of efficiency and economy he believes public interest will be far better served by not making the purchase authorized by the appropriation, and that a large amount of money may be saved to the municipal treasury by making a contract for electric lighting with a company which for many years past has illuminated a large portion of the city. It is plain under these circumstances that the respondent ought not to be compelled to spend this large amount of money for a purpose which according to his belief, apparently supported by substantial reasons, would be unwise for the city, unless absolutely compelled by some positive rule of law. There is no such compulsion to be found in the city charter of Boston or in the general laws of the Commonwealth. The appropriation of money for a specific purpose by the legislative department of the city of Boston does not make its expenditure mandatory on the executive officers in a case like the present. There is no provision of law which overrides the discretion exercised by the single justice.

R. J. Cram, for the petitioner. J. J. Corbett, for the respondent.

It is not necessary to consider the numerous other grounds for refusing the writ urged by the respondent.

Petition dismissed.

The case was submitted on briefs.

Braley, J.