92. THE KÖNIGSBERG HELIOMETER 312 93. PERTURBATIONS OF URANUS 320 94. URANUS' AND NEPTUNE'S RELATIVE POSITIONS 325 95. METEORITE 333 96. METEOR STREAM CROSSING FIELD OF TELESCOPE 334 97. DIAGRAM OF DIRECTION OF EARTH'S ORBITAL MOTION 335 98. PARABOLIC AND ELLIPTIC ORBITS 340 99. ORBIT OF HALLEY'S COMET 341 100. VARIOUS APPEARANCES OF HALLEY'S COMET WHEN LAST SEEN 342 101. HEAD OF DONATI'S COMET OF 1858 343 102. COMET 344 103. ENCKE'S COMET 345 104. BIELA'S COMET AS LAST SEEN IN TWO PORTIONS 346 105. RADIANT POINT PERSPECTIVE 348 106. PRESENT ORBIT OF NOVEMBER METEORS 349 107. ORBIT OF NOVEMBER METEORS BEFORE AND AFTER ENCOUNTER WITH URANUS 351 108. THE MERSEY 355 109. CO-TIDAL LINES, SHOWING THE WAY THE TIDAL WAVE REACHES THE BRITISH ISLES FROM THE ATLANTIC 359 110. WHIRLING EARTH MODEL 364 111. EARTH AND MOON MODEL 365 112. EARTH AND MOON (EARTH'S ROTATION NEGLECTED) 366 113. MAPS SHOWING HOW COMPARATIVELY FREE FROM LAND OBSTRUCTION THE OCEAN IN THE SOUTHERN HEMISPHERE IS 369 114. SPRING AND NEAP TIDES 370 115. TIDAL CLOCK 371 116. SIR WILLIAM THOMSON (LORD KELVIN) 373 117. TIDE-GAUGE FOR RECORDING LOCAL TIDES 375 118. HARMONIC ANALYZER 375 119. TIDE-PREDICTER 376 120. WEEKLY SHEET OF CURVES 377 PIONEERS OF SCIENCE PART I _FROM DUSK TO DAYLIGHT_ DATES AND SUMMARY OF FACTS FOR LECTURE I _Physical Science of the Ancients._ Thales 640 B.C., Anaximander 610 B.C., PYTHAGORAS 600 B.C., Anaxagoras 500 B.C., Eudoxus 400 B.C., ARISTOTLE 384 B.C., Aristarchus 300 B.C., ARCHIMEDES 287 B.C., Eratosthenes 276 B.C., HIPPARCHUS 160 B.C., Ptolemy 100 A.D. _Science of the Middle Ages._ Cultivated only among the Arabs; largely in the forms of astrology, alchemy, and algebra. _Return of Science to Europe._ Roger Bacon 1240, Leonardo da Vinci 1480, (Printing 1455), Columbus 1492, Copernicus 1543.