The association of Lady Hallé and Dr. Brodsky in Bach's Concerto for two violins yesterday brought together by far the largest audience ever yet seen at these concerts. The D minor, with two solo parts, is doubtless the finest on the whole of Bach's violin Concertos. The Largo, cast in a mould that the composer used more than once, obviously takes the first place among movements of the kind, in virtue of stately magnificence paired with a certain royal mildness and amiability of expression. Other examples may be deeper or more poignant in feeling, but none other is so richly and perfectly organised in structure or so sweetly benign in expression. The two solo instruments are treated by the composer on a footing of absolute equality, and the manner in which his intentions were yesterday realised by the two masterly performers was above praise. Why (one is likely to ask on hearing such a performance) did a composer, who could make a couple of instruments sing so sweetly and graciously and in a manner so perfectly adapted to their proper genius, very frequently force the singing voice to follow a crabbed line, instrumental rather than vocal in character? In the more vivacious movements preceding and following the Largo nothing could have been finer than the delicate interplay of the two well-matched solo parts, and the whole composition lost little or nothing by the rendering of the accompaniment on a pianoforte instead of the small orchestra for which it was originally scored. As pianoforte accompanist Miss Olga Neruda showed unfailing discretion, and so contributed not a little to the exquisite impression produced by the whole work. [Sidenote: =Beethoven B Flat Major Quartet.=] In Beethoven's B flat major Quartet--the last of the third volume--the intricate lines of the composition were brought out with admirable unanimity of purpose, perfection of _ensemble_ never once being lost amid the utmost fire and freedom of the execution in the rapid parts. The Quartet, which occupies quite forty-five minutes in performance, is remarkable for an opening movement in which adagio and allegro sections alternate with wayward frequency, for the curious fourth movement in a sort of Ländler rhythm, and for the Cavatina in E flat preceding the Finale. It is capricious and multifarious, but has neither the abstruseness nor the occasional violence of the later Beethoven as revealed in the last Quartets and Sonatas. [Sidenote: =Tchaïkovsky Quartet in D Major.=]