The abatements ordered by the board are to stand. The taxpayer is to have costs of these appeals. Boston Sand & Gravel Co. (taxpayer), contending that the taxes assessed on its real estate were excessive for the years 1958,1959, and 1960, sought abatements. The taxpayer asserted that a large portion of its property is machinery which is exempted by G, L. c. 59, § 5, Sixteenth. Abatements were granted by the Appellate Tax Board for all three years. The board of assessors appealed. Prom certain rulings of the tax board, the taxpayer also appealed. The sole issue raised by the assessors is whether the tax board erred in receiving testimony by the taxpayer’s expert witness on the value of the property, in view of the fact that the expert admitted that he had given his opinion without including in his valuation certain structures on the land. Ho requests for rulings were made by the assessors on this point, and there is nothing in the record which indicates that the tax board adopted the view of the expert that certain buildings erected to house machinery are not to be included in the valuation of the real estate. Indeed, it would appear that the tax board rejected that view, for its valuation was substantially higher than that given by the taxpayer’s expert. At all events, the assessors have failed to show that the tax hoard’s decision was tainted by error of law. That evidence was received as to the value of a portion of the property was not such error. In view of this conclusion it is not necessary to consider the taxpayer’s appeals.