The first Conn saxophones were designed by Ferdinand "Gus" (August) Buescher, a foreman at the Conn-Dupont plant from 1875-1895 (after which, he left and founded the Buescher Manufacturing company), for E. A. Lefebre. The instrument that Buescher built for Lefebre was essentially a copy of an Adolphe Sax horn.(1, 2)
These horns were produced from 1888 (3) until 1898 or so (4), and there probably were only available in bare brass, gold plate and gold plate engraved with silver highlights (see below).
These horns have double-octave keys, straight tone holes, no pearl keys and all examples probably featured a keyed range of low Bb to altissimo F. Please note the Mercedes-Benz-logo-style low C keyguard: this feature is on all Conn horns -- including stencils (and excepting the Connstellation 28M model and Col. Conn Wonder curved sopranos), until the introduction of sheet-metal keyguards.
I have found no evidence to suggest that there is an official (i.e. from Conn) model name for these horns, nor any idea of how many numbers were available -- this is because most serial number charts begin with 1895 (5), most websites do not list patents before 1920 and most of Conn's trademarks expired a long, long time ago (trademarks used to expire after 25 years) (6).
Let's look at the eBay ad for one of these horns:
CONN WORCESTER ALTO SAXOPHONE. Ca. 1890. Brass. 2 necks as shown. Early lyre. Original case missing handle. Several pads are loose and are included. All keys appear to be present, and appear to be in good condition. Body in fairly good shape with two small, superficial dents (as shown) and several very small dings. No holes, cracks or corrosion.
No serial number found.
[Colonel Charles G.] Conn started producing musical instruments with Dupont in 1876. He became sole proprietor in 1879. In 1887, Conn bought the musical instrument factory started by Isaac Fiske in Worcester, Mass. and continued to produce instruments, such as this one, at that factory until 1898 and inscribed them: "Elkhart, Ind. and Worcester, Mass."
On 03/27/02, the folks at the defunct Welch Sax website submitted a new eBay ad:
This is undoubtably the 16th saxophone made in this country. Conn bought the Fisk factory in Worchester, Massachusetts, in 1887 and a year later made the first saxophone in America. This is one is numbered 16. It is one of the most beautiful saxophones that I have ever laid eyes on. It is gold plated with about 95% of the plating intact, and the 25 leaves on the bell are all silver plated. The engraving is superb. The bow is engraved along with the bow guard. There is not a single dent in the bow. The greatest flaw is that it was made with a double octave key system. Sometime in its history it was changed over to an automatic system. This was done very, very, well, maybe even in the Conn factory. It plays to high F and low Bb. The bis key button may be a later addition. Very little of the gold plate is worn off. There is one little dent on the bell just above the joint between the bow and bell. It reads on the bell: "Made by C. G. Conn Elkhart Indiana and Worchester, Mass." One must look very hard to find the number 16 just above where the bell is attached to the bow among the flowers. There are pearls on all the front keys, the G#, and the low C & Eb. It is ready to play with new pads but you cannot take it on a gig unless it is a HP band as the instrument is high pitched. One is amazed at how modern this early saxophone is. It has features that Conn did not use again for fifty years.
This horn is definitely one of the nicest preserved horns that I have seen from this era.
Note that there are some differences between this and the brass example mentioned above: different keyguards, pearl keys, and slightly different keywork. This may be because this horn is (mainly) gold plated, and Conn (as well as other manufacturers) tended to put a bit more craftsmanship in their gold horns (compare the Evette & Schaeffer and A. Sax horns of approximately the same era, as well as the later Conn Artist horns). However, to make my life easier, I've divided these horns into a "Series 1" and "Series 2".