On 30 December 1986, a local fisherman incidentally discovered the remains of a seventeenth-century merchantman off the coast of Rincon, a small municipality on Puerto Rico's west coast. Some days later, he and some acquaintances extracted objects from the site and stored them in a nearby restaurant. The assemblage of artifacts recovered included, among other items, pins, scissors, ordnance, pewter ware, woodworking tools, a myriad of concretions and a nautical astrolabe. It is from the last that the wreck site took its name. The operation continued for months until local authorities, alerted by a member of the salvage group, issued a cease and desist order. At that point, the whole affair entered a legal process that on the summer of 2005 had not reached its conclusion. The purpose of this thesis is twofold. First, the author presents the story of the shipwreck from the moment it was found until the court ruled regarding ownership of the artifacts. Since this was the first time ownership of a shipwreck was debated in Puerto Rican courts in recent history, this gives the reader an idea of how legal precedence was established concerning the island's submerged cultural resources. Second, based on what was popularly perceived to be the site's most remarkable find, a study was developed on the sea or mariner's astrolabe, a navigation instrument that played a fundamental role in the process of European maritime expansion during the late fifteenth, sixteenth and seventeenth centuries. The reader of this text will learn that, during the fifteenth century, Portuguese navigators saw the need to gradually depart from the traditional Mediterranean navigation technique known as "dead reckoning." As their explorations along the West African coast forced them to sail far into the Atlantic Ocean for prolonged periods, a new method was developed that consisted of measuring the angle of certain heavenly bodies above the horizon in order to determine the latitude of the observer with reasonable precision. For this purpose, instruments that traditionally belonged to the field of astronomy were adapted to be used by seamen. Among them was the astrolabe, which became the most popular by the turn of the sixteenth century. After discussing the instrument's origin and development, the author analyzes how a renewed interest on the nautical astrolabe, which emerged in Portugal in the early twentieth century, introduced the instrument to the field of modern scholarly research. This work also presents a catalogue of sixteen sea astrolabes, some of which have never been published. The catalogue shows statistics and other relevant information, while placing the artifacts in the context of the previously existing data.

A map is a big multi-scale information space. The size of a computer display, however, is limited. Users of digital maps often need to repeatedly resize and reposition the map to seek information. These repeated and excess interactions mar the user experience, and create bottlenecks for efficient information processing. We introduce personalized navigation instruments, a class of navigation instruments that leverage personal important spatial entities (e.g., landmarks and routes) to tackle navigation challenges in map user interfaces. Specifically, we contribute the following three instruments, each of which embodies a novel research idea: 1) Personalized Compass (P-Compass) is a multi-needle compass that extends the concept of a conventional compass to help users establish a reference frame. P-Compass localizes an unknown reference point by visualizing its relationship with respect to landmarks. P-Compass leverages what a user knows to help them figure out what they do not know. 2) SpaceTokens are interactive map widgets that represent locations, and help users see and link locations rapidly. With SpaceTokens, users can use locations directly as controls to manipulate a map, or building blocks to link with other locations. SpaceTokens make locations first-class citizens of map interaction. 3) SpaceBar associates a simple linear scrollbar with a complex nonlinear route, thus facilitates efficient route comprehension and interaction. SpaceBar is akin to a scrollbar for a route. We prototyped these three instruments in a custom smartphone application, used the application regularly in daily life, and validated our design in two formal studies. While maps are the focus in this dissertation, our ideas need not be limited to maps. For example, we have prototyped P-Compass with Google Street View and a 3D virtual earth tour application. We conclude this dissertation with several directions for future work, such as AR/VR and personalized spatial information user interfaces involving sound, gestures, and speech.