If you had a postillion/post-boy they could also bring the horses back.
The trip from London to Edinburgh - about 400 miles - took 4 days in a post chaise in the late 18th century.
That included stopping at an inn overnight, and stopping for meals and to change horses.
So about 100 miles/day, travelling about 10 hours/day. The roads in England were generally good, by the standards of the time.
A family travelling in their own carriage would probably go slower, so about 2½ to 3 hours for 18 miles.
Most well-conditioned horses can mostly trot for 18 miles, even ridden. It is easier for a horse to pull a vehicle than to be ridden. Heck, I’ve ridden twenty miles in a day myself from time to time. Not, thank God, trotting. There is a reason endurance riders pre-load the morning of a a race with NSAIDS.
In the popular modern sport of endurance riding, a common race length is 50 miles which the top riders finish in about 6 hours; the pace is mostly a strong trot interspersed with cantering. Very little walking!
A heavy carriage horse would go much slower of course but still the normal pace for any driving horse is a brisk jog or trot, not a walk. Indeed horses bred to drive (and they still exist) have conformation selected for maximizing ease of trotting.
Horses in heavy work are not grazed except at night. They can’t get enough calories that way even if they grazed all day. They are “baited” with concentrated food during short rest periods. In Austen’s time that would have been most usually oats; now it’s a high-performance blend of ingredients.
A few years late in reply but here goes. Jane Austen writes in her diary that it took a day to travel from her parents home in Steventon, Hampshire to Devizes via Andover. A distance of about 42 miles. This she traveled by ‘chaise’ in November with her sister and mother on their way to Bath.
In November the average day light hours is 8. They would not have wanted to travel in the dark. Roads would be toll roads, Austen mentions paying tolls but there is no mention of changing horses that I have found. One may assume they took packed luncheon as I’m not too sure three ladies would break their journey at a wayside inn. So finger in the air, 6mph would seem about right.
Addendum. Austen also writes that they traveled home from Bath in one day, this was in May. Assuming they took the same route via Andover this would be 67 miles, May daylight hours are roughly 15.
Was the highwayman still a problem by 1800? I assumed it was a 1600’s to earlier 1700’s problem, and more law and order was established by the 1800’s?
James, or Robert, Snooks was executed for highway robbery in 1802, the last man un England to be condemned for this crime. This is just within Austen’s period. The new law-enforcement bodies, improved roads and enclosures in the last decades of the 18th century made highway robbery a difficult proposition.
Robbing of travellers still took place, as it still does, but such incidents were uncommon, were well-reported, prompted police action and offenders were often caught promptly (based on Old Bailey and other trial records).
People tried to travel in daylight hours, although less for fear of highwaymen than because the roads were unlit away from towns and many were still in very poor shape. Many social events were timed to take advantage of both longer summer days and moonlit nights.
Austen’s England was undergoing all manner of convulsions from the Industrial Revolution, which elevated crime, but primarily urban and property-related. Civic society relied on a police and justice system strongly geared to protecting the interests of the propertied, affluent and well-born. It didn’t stop crimes like highway robbery, but it made it hard for robbers to make a career of it.
I would imagine travel would be unwise at night as you say, simply because in the days before electric headlights, your option was a lantern. I don’t know how well lanterns travel on bumpy roads, and I doubt they provide good illumination. Moonlight might make things less risky, but it had limited availability. We live in a world where true darkness, the absence of artificial illumination, is extremely rare.
Regarding night travel, somewhere in Austen is a comment about scheduling evening dances for nights when the moon will be out.
And she herself estimates the rate of carriage travel at under 6 mph, since Lyme, their destination, is 17 miles away, and the round trip will take over seven hours. This is for a family carriage carrying 4 or more adults on country roads. When they do leave, after breakfast, they don’t arrive until “so much past noon” that they can tell that the sun will be down before too long.
Here’s the passage:
“The first heedless scheme had been to go in the morning and return at night; but to this Mr Musgrove, for the sake of his horses, would not consent; and when it came to be rationally considered, a day in the middle of November would not leave much time for seeing a new place, after deducting seven hours, as the nature of the country required, for going and returning. They were, consequently, to stay the night there, and not to be expected back till the next day’s dinner. This was felt to be a considerable amendment; and though they all met at the Great House at rather an early breakfast hour, and set off very punctually, it was so much past noon before the two carriages, Mr Musgrove’s coach containing the four ladies, and Charles’s curricle, in which he drove Captain Wentworth, were descending the long hill into Lyme, and entering upon the still steeper street of the town itself, that it was very evident they would not have more than time for looking about them, before the light and warmth of the day were gone.”