- 3508 - Joseph Henry - an American Teacher. Joseph Henry born December 9, 1797 in Albany, New York, was a teacher at Albany Academy at age 29. In 1829, at age 32, he lectured at Union College, age 35 was appointed professor at Princeton, at age 54 lecturer at Harvard. Died May 15, 1878, as president of the Philosophical Society in Washington D.C. at age 81.
--------------------- 3508 - Joseph Henry - an American Teacher
- As a teacher Joseph Henry believed students learned-by-doing. He was the first American teacher who believed his job was to spark the students interest and to provide practical experience in applying principles to everyday life.
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- He was the first teacher to use visual aids and demonstrations were the core of his teaching. The state of education in the 1830’s was usually limited to reading, writing, and ciphering. Teachers were not trained. The first public teacher-training school appeared in Massachusetts in 1839.
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- When Henry took his job in Albany the qualifications for teaching were a good moral character, a thorough knowledge of spelling, reading, and writing, and a willingness to accept the low salary offered of $8 a month.
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- Schools were overcrowded often 60 to a class with inadequate lighting and poor ventilation. Henry wrote the he expended an “ immense amount of physical energy in the vain attempt to keep order while his attention should be wholly occupied with the class under his immediate instruction. Although he used the rod sparingly he once said “ as usual I am busily engaged in applying BIRCH to one end and ARITHMETIC to the other.”
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- Teachers used “monitors” where the more advanced students taught rudiments to the less advanced. There were very few textbooks. So, Henry was the first to introduce blackboards to the American classroom.
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- He would fill the blackboard with drawings of apparatus, theorems, examples, and problems to be solved. Students would laboriously copy the blackboard into their notebooks. (Although the blackboard was erased many of the lectures are saved in student notebooks now available at the Smithsonian Institute.)
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- At that time most teachers considered knowledge as static and relied on rote drilling and memorization. There was little concern with stimulating intellectual curiosity or making use of student’s interests to encourage learning.
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- Henry brought to education his own philosophy based on his own experiences and observations. He felt that in educating an individual “ we ought to follow the order of nature and adapt the instruments to the age and mental stature of the pupil.” He advocated “providing every pupil with the opportunity of passing step-by-step the whole series of graded courses“.
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- To get students attention and to spark an interest he developed unique demonstrations. Schools had no money for this so Henry had to build his own apparatus out of common materials.
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- He bought a bar of iron and took it to the local forge to bend it into a horseshoe. He made an electro-magnet by insulating copper wire in 30 foot lengths using cotton or silk. Then stringing 26 of these 30 foot lengths to wrap around the bar magnet. (The story was told that he used his wife’s petticoats for this purpose - her sacrifice to science).
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- He built his own batteries using 9 x 12 inch zinc plates surrounded by a copper envelop. Eleven plates per battery with eight batteries connected in series. To activate the batteries he used a crank to lower or raise cups of acid into which the battery plates were immersed.
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- The power of magnets was shown to the class by lifting 1,500 pounds six inches off the floor. A student would slowly withdraw the acid and suddenly the weight would come crashing to the floor. He said it never failed to produce a great sensation.
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- Sometimes he used students pulling on ropes looped through several pulleys to demonstrate the magnet’s holding power.
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- He made compass needles out of watch springs, magnetizing them, then supported them in a stand with a fine sewing needle as a pivot. Placed on the side of the electromagnetic the needle would spin around and align with the magnetic field when a mercury switch was turned on.
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- Henry demonstrated centrifugal force by spinning a dish of mercury suspended on a twisted string. He illustrated capillary action by putting blue ink in a bowl in which he inserted a glass tube filled with sand.
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- He stretched a cotton rope over a number of pulleys and on the free end fastened a pointer which could move up and down against an index as the rope expanded and contracted in proportion to the moisture in the atmosphere on any given day.
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- Henry’s demonstrations became more than teaching tool, in 1835 he was credited for inventing the electric relay. With that he invented the telegraph connecting relay to relay over huge distances.
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- In 1830 he discovered the principle of induction, how electric current in one coil could set up a current in another coil through the development of the magnetic field. In 1831, at the age of 34, he published a paper describing the electric motor.
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- He even contributed to astronomy projecting the image of the Sun on a white screen in 1848 (age 51) and by sensitive measurements of heat, showed that sunspots were cooler than the rest of the Sun.
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- When Henry died the President of the United States, Rutherford B. Hayes, attended his funeral. In 1893, the unit of inductance was named the “henry“.
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- Faraday’s law of mutual inductance states that the electromagnetic force induced in wire loop 2 is equal to the rate of change of the current in wire loop 1 times the magnetic flux divided by current.
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-------- 1 henry = 1 weber / ampere = 1 kilogram *m^2/ ampere^2 * sec^2
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- Henry believed that active research was an important function of a good teacher. He believed that a teacher would gain clearness of concept imparting knowledge to others and in answering questions posed by students would gain new insights into the phenomena he is teaching.
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- At age 57 he wrote, “he has not lived in vain who leaves behind him a child better educated morally, intellectually, and physically than himself.”
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------------------------- Joseph Henry - one of America’s great teachers.
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March 18, 2022 Joseph Henry - an American Teacher. 531 3508
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