Henry’s Magnet Today

The current state of Henry’s magnet today seems chaotic at first, but with a closer look one can see that the setup is fairly simple.

Magnet Video

Magnet Video 2

The Magnet at Princeton weighs 24 pounds and is about 9 1/4 to 9 1/2 inches tall. This seems about right when you factor in the weight of silk insulation and 9, 60 ft copper coils. The armature was found in the Jadwin Hall display case, sitting on the shelf below the Magnet behind a large galvanic battery, almost completely out of sight. It weighs 7 pounds, measuring 2 inch square by 6 3/4 inches long, which matches the description in Henry’s paper. The magnet shows two large solder connections, each made with 9 strands of wire coming in/out. These 9 strands can easily correspond to Henry originally having 9 separate 60 ft coils. However, there is a 3rd, smaller, solder connection made with 6 strands of wire. How was the magnet really wound?

AAt first glance, the windings seem disorganized, but upon further examination, several identification tags can be seen attached along each strand. These tags are all different. Each tag seems to be paired with another, being different only by a single dot or hole in the center of the tag. This suggests that Henry labeled one end of each strand with a symbol or dash, and the other end with the same symbol or dash plus a dot or hole in the middle of the label.

Each strand of wire seems to be wrapped in either tan or green linen. There are 5 green wires and 4 tan wires coming from the first large solder connection. Let us call this connection the blue connection. There are also 5 green wires and 4 tan wires coming from the other large solder connection. Let us call this connection the orange connection. There are only 2 green wires and 4 tan wires coming from the small solder connection, let’s call this connection the black connection. It is possible that Henry alternated between green and tan linen. Furthermore, most of the tan wires are wrapped around the left side of the horseshoe, and most of the green around the right.

Originally, Henry documents that “540 feet of copper bell wire were wound in 9 coils of 60 feet each”. Let us assume Henry insulated 5 of the 9 wires in green linen and the remaining 4 with tan linen. In experiment 17, there were “wires, each 30 feet long, attached to the galvanic element, the weight lifted was 375 Ibs.” This suggests that he would have cut 3 of the 60 ft strands of wire in half, creating 6, 30 ft strands. Let’s assume that 2 of the 3 60 ft wires that he cut were wrapped in tan linen, and the remaining strand was wrapped in green linen. If this is accurate, it would agree with the black connection having 4 tan wires and 2 green wires.

A closer observation of every strand of wire coming out of each solder connection was made. Each strand was followed from each connection to the point of entry into the windings along the horseshoe.


Back Camera

These locations were recorded on the drawing above, along with a sketch of each tag associated with each wire. Each tag was colored tan or green – identifying what color linen was used for insulation. They were outlined with either blue, orange, or black – identifying which solder connection it was from. The tags that were bent together and unreadable were marked as a small square.

From this outline, we can suggest that 2 tan and 1 green wire from the black connection are connected through coils to the blue connection, and another 2 tan and 1 green wire are connected through coils to the orange connection.

The resulting circuit consists of 6, 60 ft coils in parallel with 3 pair of 30 ft coils in series (A total of 12 wires). The suggested circuit diagram is shown below.