Without a system of rapid communications, weather forecasting in any meaningful sense is quite impossible. It is only by analysing the existing patterns of temperature and pressure over a wide area that the forecaster can identify weather systems and predict their arrival.
If the basic information takes too long to come, the forecasts will be "history" even before they are prepared. This was the great dilemma facing early meteorologists.
In April 1791 there was unveiled in Paris a device which some felt might be a solution to the problem. The "optical telegraph" was the brain-child of an engineer called Claude Chappe: provided everyone did their job properly, it was capable of transmitting information from one end of the country to the other rapidly.
The system consisted of an array of large machines with mobile arms like railway signals. They were strung out in a line along the desired route, and each was sited on a tower on the highest ground in the locality, visible to its immediate fellows "fore and aft".
An operator in each tower was equipped with telescope and code book, and messages were relayed along the line by semaphore.
You may remember that the device featured in The Count of Monte Cristo, when Edmond Dantes bribed one of the operators in the chain to distort an important message before it was passed on, thereby bringing financial ruin to one of Dantes's enemies.
This cumbersome instrument is little thought of nowadays. But in that same year of its invention, 1791, there was born in Charlestown, Massachusetts, an individual who was to make the dreams of rapid and efficient communication over great distances realisable, and in the process ensure the viability of weather forecasting as an operational science.
Samuel Finley Breese Morse had devised a working model of the electric telegraph as early as 1837, and subsequently thought up the clever code of dots and dashes which allowed a text to be transmitted by means of long and short pulses.
It was several years later, however, that the first official telegraphic message was transmitted, being sent down an experimental 40-mile line specially installed from Washington to Baltimore.
That famous first transmission took place 155 years ago today, on May 24th, 1844.
Its content was somewhat enigmatic: "What hath God wrought" is a quotation from the Book of Numbers, and its relevance to the exercise is a matter of conjecture.
But it was the medium rather than the message that revolutionised the world, and meteorology.