CITY OF BOSTON.

EXECUTIVE DEPARTMENT,

CITY HALL, BOSTON, July 28th, 1873.

TO THE CITY COUNCIL OF THE CITY OF BOSTON:

I have the honor to transmit herewith the report of the Commission appointed under the authority of an order of the City Council of 1872, to investigate the subject of Wood Pavements, and the methods of preserving the same.

HENRY L. PIERCE, Mayor.

CITY OF BOSTON.

TO HIS HONOR THE MAYOR:

The Commissioners appointed to investigate the matter of Wooden Pavements, etc., have the honor to submit the following report, viz. :—

This commission was appointed by his Honor Mayor Gaston, on December 17, 1872, in pursuance of an order of the Board of Aldermen, passed August 26, 1872, and approved by the Mayor, September 3, 1872.

The order of the Board of Aldermen was as follows, viz. : "That his Honor the Mayor be authorized to appoint a Board of Commissioners, consisting of two chemists, two practical mechanics, and one engineer, to make a thorough investigation of the several processes in use, or available for protecting wood to be used for paving from decay, and the various methods of constructing and putting down wood and stone pavements, and report to this board their opinion of the relative merits of the same.

"Ordered, That a premium of three hundred dollars be offered for the best essay on the most effectual method of preserving wood pavements from decay in this city, said essays to be submitted to the foregoing commission at such time as they shall publicly designate."

The first meeting of the commission was held at the office of Shedd & Sawyer, in Barristers' Hall, December 20, 1872, when organization was effected, by the choice of Edward Sawyer as President, and J. M. Merrick, Secretary.

Public notice was given in the daily journals that the com

mission would give hearings to all interested parties, and then such meetings were held in the City Hall.

Patentees and parties interested in wooden pavements and the preservation of wood appeared at these hearings, and set forth their views and the merits of their processes, etc., etc.

The Commissioners have held numerous private sessions, at which the matters in question have been thoroughly discussed, and they have also visited and inspected various pieces of wooden pavement in this city.

They have declined invitations to visit other cities at the expense of the persons inviting them.

As the result of their labors, they submit this report, which takes up, first, the matter of the preservation of wood, and secondly, the construction and laying of pavements.

PRESERVATION.

In regard to the matter of the preservation of wood for paving purposes, your Commissioners have to say that they have patiently and diligently sought for information upon the subject, and have listened to the statements of numerous patentees and interested parties. Each process is very warmly praised by those interested, and the patentees of one process fail of course to see any merit in their competitors' methods of preservation.

So far as your Commissioners know, there is no wooden pavement in this city, which has been down long enough to afford a proper test, which does not show considerable deterioration, owing either to defective treatment, or defects in construction; and they have not been able to find a preservative process cheap and efficient enough to be recommended to the city without qualification.

The leading processes brought to your Commissioners' notice are,

I. Treatment of the wooden blocks with hot oil— the socalled dead oil, and other similar oils.

Of this it may be said, that the complete saturation of the wooden block with dead oil affords perhaps the most perfect preservation it is possible to attain, but this method must be put entirely out of the question, on account of the expense the use of the large quantity of oil required necessarily involves, and the slipperiness of the surface of the blocks.

The partial or incomplete treatment of the wooden blocks with oil or tar can hardly be recommended, and especially is the practice of tarring each end of the blocks to be avoided, as in this case the wood inevitably rots in the middle.

It is claimed that a partial saturation of the blocks with oil, under proper conditions, will add much to their durability, preserving them, in fact, for an indefinite time. While this may be the case, your Commissioners have no positive proof that this process will do its work well enough to justify them in recommending it to the city.

II. Kyanizing, or the treatment of wood by long immersion in a solution of chloride of mercury, is undoubtedly a very effective preservative process; but your Commissioners believe it is inapplicable for two reasons, viz. : its expense, which is large on account of the cost of the salt of mercury, and also on account of the danger to the health of the workmen employed.

III. Burnettizing, or treating wood with a solution of chloride of zinc, seems to be the process to which in practice we are reduced; and here the evidence laid before the commission has been of a rather contradictory nature. Many discrepancies in the statements brought to us may have had their origin in the fact that wood said to have been burnettized had not been treated at all, or had been imperfectly treated; but making allowances for this, there seem to have been some cases in which this treatment has failed to add to the durability of wood. Still, in the great majority of cases, so far as your Commissioners are informed, it has succeeded reasonably well. It should, however, be borne in mind, that