Science and Technology in the Edo Period

57cm in height and decorated with cloisonné, lacquer work and mother-of-pearl, this large standing spring-driven click was made in 1851 by Hisashige Tanaka (1799-1881), a prominent engineer during the late Tokugawa era to the early Meiji period, after spending nearly a rear on the project.The six dials at the top features Western and Japanese time dials, as well as weekly, monthly and zodiac settings. On the upper part is an astronomical dial mechanism and the old Japanese temporal hour system of employing the time of sunrise and sunset in particula indicate Tanaka's high level of mechanical expertise and deep knowledge of nature science. Japan was capable of smoothly adapting Western science and technology in the Meiji period owing to the foundation laid down during the Edo period. The Myriad-Year Clock is a historical monument symbolising Tanaka's contribution in bridging science and technology from the Edo period to Meiji period. 

This is acolor development technique which draws out the gold color in gold and silver dlloy and has proven to be moredurable than planting. During the Edo period, the ratio of gold to silver in the koban varied from year to year, leading to the possibillity of some obans and kobans haveing a stronger silver appearance than other. This redying technique was performed to alleciate this situation. It is said that the use of this method is cofirmed in ancient Inca artwork. According to Japanese tradition, however, this method is believed ti have been passed down as the secert medhod employed by the methalsmith "Goto Shirobei-Ke" and was used in Obanza and Kinza (oban and gold mint). Literatures use the, irotsuke (dying), and later iroage (redying). With this method, the koban is coated with a dye and heated, the silver portion is extracted from the gold and silver surface, and the remaining gold is recrystallized to form a gold-enriched layer. 

The abacus has been popularly used by many people in modern times, however most wazan scholars, used the "sangi" or counting rods, a calculation tool used since ancient times. Under this method, counting rods are arranged and calculated according to the decimal system. THe wooden or paper board used to maneuver the counting rods is called the calculation board. Lines are drawn along the matrix lines and the counting rods are placed inside the squares. This is somewhat a roundabout method of calculation, but has proven to be a more sophisticated method of calculation (processing of equations of higher degree) than the abacus.

The Japanese characters for "survey" come from a Chinese expression meaning "Gauge the sky, weight the earth." In the Edo Period, surveying techniques spread as practical skill as Western astronomical and surveying knowledge blended with traditional Japanese surveying techniques. The civil engineering, flood control, and miniing projects that proliferated in the Edo Period were only possible because of the widespread diffusion of surveying techniques.

In order to accomplish his purpose of surverying the whole nation of Japan and to measure the distance of 1 degree latitude, Tadataka Ino needed to make accurate astronomical observations throughout the country. The quadrant was one of the surverying equipments used to measure the position of the stars. It was made with reference to the Reidaigishoushi (1674) under the order of master Shigetomi Hazama. There were two quadrants: the large-size quadrant measuring 6 shaku ( or approximately 180 cm) in radius and the middle-size quadrant measuring 3.8 shaku ( or approximately 115 cm) in radius. The middle-size quadrant was used for the nationwide surverying project.

Drawing tools used is surveying during the Edo period differed slightly depending on the school and year, but were basically tools shich indicated the direction and distance of a location on a smaller scale drawing. Directions were indicated by angles inscribed on the bundono kane (a combination of a circular protractor and ruler), circular protractor, semicircular protractor and quarter circle protractor. The reduced-size drawings were made using the compass and ruler. Like the hoshibiki and subiki which were used to draw dotted lines, pen type writing tools from the West were already utillized during the Edo period. Circular protractor, quarter-circular protractor (or sextant), semi-circular protractor, hoshibiki, compass, needle.