solar compass original patent of 1835 that was about to expire. The land commissioner committee, which consisted of senators from Michigan and other states, recognizing the value of Burt's solar compass in public land surveys, persuaded him to forego renewal and petition congress for suitable advance compensation. Burt did as was suggested believing that he would be compensated appropriately. However, the compensation indicated did not materialize in Burt's lifetime or at any time thereafter. Since there was no patent on Burt's solar compass after 1850, instrument makers manufactured and sold "Burt's solar compass" to surveyors as a commercial product. The inventor spent thousands of dollars to perfect his instrument, but only received eighty dollars in sales of his tool for his labors. In the preface to his Key to Solar Compass and Surveyor's Companion (1858) by his associate William S. Young, Burt refers to the many requests for such a book on how to use his solar compass. He explains that the common surveyor's compass had problems with the true meridian at different localities. It also had problems from day to day with different readings from that expected as a constant or from previous readings. It was determined that a magnetic compass was prone to interference from the local attraction of iron ore. A more accurate guide for the surveyor was desired, so the solar compass was created by Burt. Surveyor Bela Hubbard noted in 1845 that with Burt's solar compass they could survey a straight line through iron-rich country, which would have been an impossible task using the normal compass instrument. The original impetus for Burt's solar compass was for use where the old fashion compass was vulnerable to large land iron deposits that made unusable readings. It was then found to be superior in general to the common compass, even when local iron ore deposits were not a problem. A solar compass attachment to the surveyor's transit was still the recommended method for obtaining the true north direction as instructed in the 1973 surveyor's manual of the US Bureau of Land Management. The instrument was widely adopted for surveying land in the United States and mandatory for government surveying from the mid-nineteenth century until the year 2000, when the satellite Global Positioning System technology became the preferred method of surveying. Description Principle of operation Surveyors can locate true north by viewing the Sun or other astronomical objects like