Abstract: A stringed instrument soundboard is provided, including composite structure that includes first and second opposed layers of a stiffened graphite sheet material and a low-density core material interposed between the first and second opposed layers. Methods of making the soundboard and stringed instruments including the soundboard are also provided.

Abstract: The invention features an elevation-sensing system comprising an elevation-sensing instrument which includes a sighting device having an optical axis for aiming at an object and an electronic elevation-angle sensor attached to the sighting device and having an electrical characteristic indicative of elevation angle relative to an axis of the electronic elevation-angle sensor and a repeatability of at least 6 arcminutes over an angular range of said electronic elevation-angle sensor, and a processor for deriving an elevation angle from the electrical characteristic.

Abstract: A soundboard for an acoustic guitar is made of a composite-materials plate having an area density matching that of wooden soundboards while having a bulk density exceeding the bulk density of wooden soundboards. The soundboard is preferably made of a lay-up of woven polymer (preferably aramid) fabric and a layer of unidirectional graphite fibers followed by a layer of decorative fabric (e.g., silk), all embedded in a resin matrix. The side and back are made of at least one layer of woven fabric embedded in a resin matrix. The neck is made of a foam plastic core preferably covered with a woven fabric layer and a decorative fabric layer embedded in a resin matrix. The head is preferably cast of fiber-filled thermoplastic covered with a fabric layer embedded in a resin matrix. The head and neck are channelled to receive a composite-materials reinforcing rod, a fret board of similar material being bonded thereto.

Abstract: A soundboard for an acoustic guitar is made of a composite-materials plate having an area density matching that of wooden soundboards while having a bulk density exceeding the bulk density of wooden soundboards. The soundboard is preferably made of a lay-up of woven polymer (preferably aramid) fabric and a layer of unidirectional graphite fibers followed by a layer of decorative fabric (e.g., silk), all embedded in a resin matrix. The side and back are made of at least one layer of woven fabric embedded in a resin matrix. The neck is made of a foam plastic core preferably covered with a woven fabric layer and a decorative fabric layer embedded in a resin matrix. The head is preferably cast of fiber-filled thermoplastic covered with a fabric layer embedded in a resin matrix. The head and neck are channelled to receive a composite-materials reinforcing rod, a fret board of similar material being bonded thereto.

Abstract: A sextant for indicating the angular separation between two objects, including two members interconnected at a pivot point, means for adjusting the angle between the members to be indicative of the angular separation between the objects, the means for adjusting including coarse and fine adjustment means, and a pair of encoders for converting the respective positions of the coarse and fine adjustment means to signals which are together indicative of the angular separation. In other aspects, there is a single encoder having a track on the sextant arc and a sensor on the tangent arm; and an indicator tells the user when the sextant has been set to the prestored altitudes of reference celestial bodies.

Abstract: A sextant for indicating the angular separation between two objects, including two members interconnected at a pivot point, means for adjusting the angle between the members to be indicative of the angular separation between the objects, the means for adjusting including coarse and fine adjustment means, and a pair of encoders for converting the respective positions of the coarse and fine adjustment means to signals which are together indicative of the angular separation. In other aspects, there is a single encoder having a track on the sextant arc and a sensor on the tangent arm; and an indicator tells the user when the sextant has been set to the prestored altitudes of reference celestial bodies.