In the collection of relics of the great master, in the possession of the Marquis Dalla Valle, there are some items which appear to be connected with this most interesting letter: I refer to the designs for a case, or cases, for a concerto of instruments dated 1684, which Stradivari himself describes as being for the Grand Duke of Florence. The date upon these designs is indicative of the order for the Violins and the Violoncellos having been given in that year (1684) by the Marquis Ariberti, who at the same time gave certain instructions as to cases and armorial designs. The completion of the order, however, appears to have been delayed, and the instruments were not delivered until 1690. The instructions given in the above letter to Stradivari to complete the concerto by making the Tenors (the patterns of which are among those in the possession of the Marquis Dalla Valle, signed, and dated 1690), and the existence of the Violoncello and one of the Tenors at Florence, dated 1690, are confirmatory of the opinion that the order was executed in 1690. The following inscription, under the left shoulder or side, is in the Tenor: "Prima 20 Ottobre 1690 per S. A. Da Fiorenza." It is interesting to find that the Grand Duke also possessed a Stradivari Violin, dated 1716, which is in Florence, together with the instruments above referred to. It is therefore evident that the belief of the Marquis that Stradivari would receive further orders from the Grand Duke was realised. Between the years 1690 and 1700 Stradivari made, together with the form of instrument just described, that known to connoisseurs as the "long Strad." We have here quite a differently constructed instrument; it is less graceful, although there is no absence of the masterly hand throughout the work. It has received the title of "long Strad" from its increased length, as the name would imply.[25] [Footnote 25: The usual length measurements of the various patterns are as under:-- (1) "Amatise," 13-7/8 inches. (2) "Long Strad," 14-1/8 (occasionally 14-1/4) inches. (3) "Grand pattern," 14 to 14-1/16 inches.--EDITORS.] Fortified with the experience which the variously constructed instruments referred to had enabled him to gather, he would seem to have marshalled all his forces in order to enter on an entirely new campaign, one that should be alike glorious to himself and his art. That he succeeded in achieving all that he could have desired, my readers will have an opportunity of judging by the evidence I propose to offer. It was about the year 1700 when Stradivari entered upon a new era in his art. All his past labours appear to have been only measures preliminary to that which he proposed afterwards to accomplish, and were made for the purpose of testing, to the minutest degree, the effect of particular modifications in the form and thickness of his works.