These observations have reference chiefly to the intensity of the earth's magnetism, and were made for the most part with Hansteen's apparatus, in the possession of the society.The first section of the paper refers to the method of making the observations, which is nearly that of Professor Hansteen.The second refers to the corrections applied. These are—1. for the rate of the chronometer; 2. for reduction of the vibrations of the intensity needles to infinitely small arcs; 3. for the effect of temperature in diminishing the magnetism of the needles, which was determined for each by direct experiment; 4. for changes in the earth's magnetism; 5. for progressive changes in the needle's magnetism, which were considerable for one of the Hansteen needles, but for the other very small.