This is a suit in equity brought by the selectmen of Natick under St. 1908, c. 552, § 2. The question presented is the meaning of the words of St. 1906, c. 463, Part I, § 38, as to the apportionment between the railroad and the town of the cost of maintenance of a bridge by which a highway spans the tracks of a railroad, built in pursuance of a grade crossing abolition. The physical facts of importance are that this bridge consists of main girders extending from abutment to abutment, which ultimately bore the entire weight of the bridge; across these were six floor beams; directly supported by these but with their upper plane three inches below the highest level of the floor beams were stringers or “ I ” beams, twenty-three of which were between each two floor beams. The girders, floor beams and stringers were of steel. On top of the stringers was laid the under floor of hard pine planks three inches in thickness. By these the elevation of the whole was brought even with that of the floor beams. Over all was laid the wearing surface of two inch spruce planks. Additional special flooring for the street railway tracks is not here material. There was testimony which was not contradicted, and appears to have been accepted as true, that the general purpose of the plan of two sets of planks was economy and safety, in that the wearing surface could be replaced as deterioration by use required, while the under floor which served as a general support for the traffic, being not directly exposed, would last much longer. There was also evidence, which does not seem to have been controverted, that the under flooring in bridge construction is always designed to be of *232strength sufficient to support the load of travel, while the wearing surface planks do not add strength. While bridges sometimes are built of one layer of planks of greater thickness, the better and prevailing practice seemingly is to use two layers of planks of different thickness and variety of wood. The upper planking in this bridge has worn out and been replaced from time to time by the town. Now the under planking needs to be renewed. The point to be decided is whether the railroad or the town shall bear this expense. The material words of the statute are “ the expense of maintenance and repair shall be paid as follows: . . . the framework of the bridge and its abutments shall be maintained and kept in repair by the railroad corporation, and the surface of the bridge and its approaches shall be maintained and kept in repair by the city or town.”
There was a hearing before a judge of the Superior Court, who filed a memorandum. Although its phrase is not wholly clear, we understand it to be a ruling of law upon the physical facts above stated, and not a finding of fact, that the under planking is not a part of the “ framework.” As a general rule, the language of a statute is a matter of law for interpretation by the court, and is not a subject as to which evidence of the meaning of words employed would be competent. We are aware of no instance where the narrow rule permitting explanatory evidence, from those possessing expert knowledge, touching the meaning of words obviously used in a technical or peculiar sense in a written instrument has been extended to statutes. Brown v. Brown, 8 Met. 573, 576. Ford v. Tirrell, 9 Gray, 401. Easton v. Smith, 20 Pick. 150, 156. Federal Ins. Co. v. Gilmour, 206 Mass. 203. The opinions of individual legislators who framed the statute would have been inadmissible. Browne v. Turner, 174 Mass. 150, 154. United States v. Trans-Missouri Freight Association, 166 U. S. 290, 317, 319. But the trial judge does not appear to have proceeded on the theory of such extension of the rule. The physical construction of the bridge being explained, he treated as a question of law what was “ framework ” to be kept in repair by the railroad and what was “ surface ” to be repaired by the town. The correctness of his ruling of law appears to be fairly open by the exceptions.
“ Framework ” as applied to things built or constructed means *233that which furnishes form or strength, or both. It is used here as the antithesis of “ surface.” It is clear that “ surface ” is not employed in its geometrical sense as signifying a plane. It includes obviously some degree of thickness.
The report of the commissioners provided that “ the superstructure of said bridge shall be built of iron or steel, with hard pine underfloor and spruce plank wearing surface.” This language seems to indicate that they treated the superstructure of the .bridge as consisting of two main features, the iron or steel on the one side and the under floor and wearing surface on the other side. In other words it consisted of the steel framework and the double flooring which was the surface of a continuous roadway. The use of the words “ wearing surface ” has some tendency to show that the spruce plank constituted only a part of the “ surface ” mentioned in the statute, while the words “ under flooring ” likewise tend to indicate a fraction to be united with that which is above in making a single unit. This unit must be the “ surface ” mentioned in the statute. “ Surface” is used in contradistinction to “ framework ” and is tantamount to flooring when one considers a bridge as a whole, to be kept in repair in part by a railroad and in part by a town. The rail- ' road furnishes the support or “ framework ” for the road or “ surface ” which the town is to maintain. If the report of the commissioners had required but one layer of planks five inches in thickness, that plainly would have been all “ surface.” The fact that two layers, each of thinner planks, were ordered does not affect the substance of the matter, which was in fact the surface of the street as distinguished from the supporting framework.
In the division of the wlple structure of a bridge into these two parts, the word “ framework ” has some tendency to point out that which constitutes the carrying strength of the bridge, while “ surface ” seems more nearly to relate to that which within the limits of the carrying strength supports the immediate burden of travel. Both layers of planks are needed for this latter purpose.
This interpretation seems more simple, direct and natural, and avoids some troublesome questions of liability which might arise if the maintenance of different layers of plank laid one *234upon the other were apportioned to different parties. While the question is a close one, we incline to treat the word “ surface ” as including all the flooring.
Leary v. Boston Elevated Railway, 180 Mass. 203, does not appear inconsistent with this view, for there the language under discussion was “ surface material of streets ” in connection with “ paving ” and “ upper planking,” thus differing materially from that here construed.
Exceptions overruled.