A reliable catalog of earthquake locations and magnitudes spanning long periods of time is a fundamental requirement for a wide variety of seismological studies, including seismotectonics, Earth structure, and seismic hazard. On a global scale, the most comprehensive source of earthquake locations, phase data, and magnitudes is the Bulletin of the International Seismological Centre (ISC). Locations, magnitudes, the data used to compute them ( i.e. , phase arrival times and amplitude/period readings), and other data are collected and processed at ISC and made readily accessible in digital form (Willemann and Storchak, 2001). ISC, which published its first bulletin for the year 1964, was established to continue the task of the International Seismological Summary (ISS), the organization that compiled phase arrival times and earthquake locations from observatories and agencies all over the world and produced bulletins from 1918 to 1963, both inclusive. Unlike ISC, which was constituted as an international nongovernmental center funded by institutions from various countries, ISS was essentially a British enterprise, and its origin can be traced back to the work of John Milne. A detailed account of the history of ISS can be found in Stoneley (1970). The level of completeness of the ISC Bulletin and the easy data availability in digital form make it the preferred source for global and regional studies. Conversely, the ISS bulletins are available only in printed form and therefore any quantitative study of pre-1964 seismicity (hereafter referred to as early instrumental seismicity) using arrival-time data involves first the tedious and time-consuming task of hand-entering the observations from the ISS bulletins. This circumstance has effectively limited the use of ISS data for global studies, including the systematic analysis and relocation of early instrumental seismicity using modern, advanced techniques. A long-term project is currently underway to convert the ISS data to digital form …