Temple's Diary
A Tale of Benjamin Franklin's Family
In the Days Leading up to The American Revolution
I asked Dr. Franklin why he kept measuring the sea's temperature. He was delighted by my question and gave me a whole lecture on that warm current, a kind of river within the sea, that is called the Gulf Stream. For various reasons, it is extremely important for sea captains to map its course. One reason is that if a merchant ship manages to sail on it, it will move along much more quickly, at less expense, and be able to deliver its cargo sooner. The reason some ships take so much longer to cross the Ocean is that they are sailing against the Gulf Stream's current and have to struggle against its strength.
Charting it properly, he told me, is also essential for another economic reason, since whales, in order to keep comfortable in the frigid waters, swim along the edges of the Gulf Stream. Having an accurate chart thus makes it easier for the whaling captains to capture them and extract their precious oil so useful for lighting and a whole lot of other purposes. The existence of this current has been known for a long time but precise information about it is kept secret by the few who are in the know.
The big whaling center, he said, is the island of Nantucket, and since his mother came from Nantucket, he has many relatives over there who are just as eager as he is to learn more about the Gulf Stream.
Would I care to help him? Of course I would. I am becoming so bored that I even miss my French classes with all their tricky genders and irregular verbs. Apart from taking the sea's temperature at various times of day and evening, to verify that Gulf Stream water is really warmer than the sea it runs through, I have to look out for what he calls "Gulf weed" and also take notice of whether or not the water sparkles in the night. Gulf Stream water, says the Doctor, does not sparkle in the dark. And he handed me the chart which I am reproducing here. This is great fun.
| Date | Hour | Temp of air | Temp of Wats. | Wind | Course | Distance | Latitude N | Latitude W | Remarks | |
|---|---|---|---|---|---|---|---|---|---|---|
| April | 10 | 62 | ||||||||
| 11 | 61 | |||||||||
| 12 | 64 | |||||||||
| 13 | 65 | |||||||||
| 14 | 65 | ° ′ | ° ′ | |||||||
| 26 | 60 | 70 | 37 39 | 60 38 | Much gulph weed; saw a whale. | |||||
| 27 | 60 | 70 | S S E | W b S | 37 13 | 62 29 | Colour of water changed. | |||
| 28 | 70 | 64 | S W | W N W | 37 48 | 64 35 | No gulph weed. | |||
| --- | 6 P.M. | 67 | 60 | 34 | Sounded, no bottom. | |||||
| 29 | 8 A.M. | 63 | 71 | N | W | 44 | 37 26 | 66 0 | Much light in the water last night. | |
| --- | 5 P.M. | 65 | 72 | N E | 57 | Water again of the usual deep sea colour, little or no light in it at night. | ||||
| --- | 11 dit. | 66 | 66 | N WbN | W b S | |||||
| 30 | 8 A.M. | 64 | 70 | N E | W b N | 69 | ||||
| --- | 12 | 62 | 70 | E b S | 24 | 37 20 | 68 53 | Frequent gulph weed, water continues of sea colour, little light. | ||
| --- | 6 P.M. | 64 | 72 | E S E | W b N | 43 | ||||
| --- | 10 dit. | 65 | 65 | S | 25 | Much light. | ||||
| May | 1 | 7 A.M. | 68 | 63 | 60 | Much light all last night. | ||||
| --- | 12 | 65 | 56 | S S W | W N W | 44 | 38 13 | 72 23 | Colour of water changed. | |
| --- | 4 P.M. | 64 | 56 | W b N | 21 | |||||
| --- | 10 dit. | 64 | 57 | S W | W N W | 31 | Much light. | |||
| 2 | 8 A.M. | 62 | 53 | 18 | 38 43 | 74 3 | Much light. Thunder-gust. | |||
| --- | 12 | 60 | 53 | W S W | N W | 18 | ||||
| --- | 6 P.M. | 64 | 55 | N W | W S W | 15 | ||||
| --- | 10 dit. | 65 | 55 | N b W | W b N | 10 | ||||
| 3 | 7 A.M. | 62 | 54 | 30 | 38 30 | 75 0 |
