The tide-predicting machine invented by Sir William Thomson in 1872 was of great utility to navigation in shallow waters. It used a system of pulleys and wires to automatically calculate predicted tide levels for a set period at a particular location.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): When was the tide-predicting machine invented by Sir William Thomson invented?
Ah, so.. 1872

The Taira and the Minamoto clashed again in 1180, beginning the Gempei War, which ended in 1185. Samurai fought at the naval battle of Dan-no-ura, at the Shimonoseki Strait which separates Honshu and Kyushu in 1185. The victorious Minamoto no Yoritomo established the superiority of the samurai over the aristocracy. In 1190 he visited Kyoto and in 1192 became Sei'i-taishōgun, establishing the Kamakura Shogunate, or Kamakura Bakufu. Instead of ruling from Kyoto, he set up the Shogunate in Kamakura, near his base of power. "Bakufu" means "tent government", taken from the encampments the soldiers would live in, in accordance with the Bakufu's status as a military government.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): When did the Gempei War end?
Ah, so.. 1185

On 20 June 1794, Burke received a vote of thanks from the Commons for his services in the Hastings Trial and he immediately resigned his seat, being replaced by his son Richard. A tragic blow fell upon Burke with the loss of Richard in August 1794, to whom he was tenderly attached, and in whom he saw signs of promise, which were not patent to others and which, in fact, appear to have been non-existent (though this view may have rather reflected the fact that Richard Burke had worked successfully in the early battle for Catholic emancipation). King George III, whose favour he had gained by his attitude on the French Revolution, wished to create him Earl of Beaconsfield, but the death of his son deprived the opportunity of such an honour and all its attractions, so the only award he would accept was a pension of £2,500. Even this modest reward was attacked by the Duke of Bedford and the Earl of Lauderdale, to whom Burke replied in his Letter to a Noble Lord (1796): "It cannot at this time be too often repeated; line upon line; precept upon precept; until it comes into the currency of a proverb, To innovate is not to reform". He argued that he was rewarded on merit, but the Duke of Bedford received his rewards from inheritance alone, his ancestor being the original pensioner: "Mine was from a mild and benevolent sovereign; his from Henry the Eighth". Burke also hinted at what would happen to such people if their revolutionary ideas were implemented, and included a description of the British constitution:
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): Who did Burke thank in June 1794?
Ah, so..
unanswerable