From what I can find: In 1858 – when the British Raj was established – it took about half a year since you had to go around cape the good hope. After the Suez canal opened in 1869 it took only ~2 months. In the following two decades expansion of the train network and faster steamboats further reduced it to about 2 weeks.

So it really depends a bit on which period you're talking about as there were lots of things going on during the period, but for a substantial part of the British Raj's existence you could get there in a month or less.

I expect the "law" is not as simple as "1 month travel time", but rather a calculation that factors in both travel time + communication time. For much of history these two value were mostly identical, but this changed with the adoption of the telegraph (and later, radio).

The British Raj succeeded the East India Company, a London-headquartered enterprise that had effectively ruled most of India for the previous 100 years, and fought numerous wars - usually successfully - in India in the century before that. The Raj was actually a reaction to Indian rebels failing to achieve independence and more power being transferred to the British Crown as a result.

Here's a data point for you - Galton's Isochronic Passage Chart, showing the time in days to travel from London to the rest of the world, in 1881. (12 years after the Suez opened, and the map shows how useful that canal was.)

Map at https://en.wikipedia.org/wiki/Isochrone_map linking to https://en.wikipedia.org/wiki/Isochrone_map#/media/File:Isoc... .

Eastern Indian is 20-30 days. Batavia is about 30 days. Perth and Hong Kong are in the 30-40 day range. Sydney and most of the interior of Australia is in the 40+ day range, as is New Zealand's South Island.

"It assumes that there are favourable travel conditions and that travel arrangements over land have been made in advance. It assumes travelling methods of the day within a reasonable cost."

EDIT: https://archive.org/details/friendsreviewrel06lewi/page/702/... from 1853 lists routes from London to Calcutta ("Friends' review; a religious, literary and miscellaneous journal", p702):

"The distance from London to Calcutta, by the Cape of Good Hope, is 15,000 miles requiring 150 days. With steam say 70 days." ["150 days" agrees with your "about half a year."]

"The distance from London to Calcutta, by Cape Horn, is 21,500 miles requiring 215 days. With steam say 90 days."

"From Liverpool to Calcutta, by Isthmus of Panama, 14,00 miles requiring 140 days. Steam, say 60 days."

"London to Calcutta, overland route, five trans-shipments, 6,000 miles, 58 days"

"Liverpool, New York, and Railway to San Francisco, two transhipments, 12,000 miles, 35 days."

It's from a piece arguing for the usefulness of building a railway across the US (New York to San Francisco), to shorten the London/Calcutta route. That last route didn't exist until 1869, the same year the Suez Canal opened.

EDIT #2: https://archive.org/details/sim_the-lancet_january-3-june-26... has someone leaving London June 1817 and arriving Calcutta 2 December 1817, so about 5 1/2 months. (The Lancet January 3-June 26, 1852, p384, "Biographical Sketch of James Ranald Martin, Esq., F.R.S.")

EDIT #3: The clipper ship Jane Pirie, built 1847, could do the round-trip in "eight months and a half ... the ordinary time occupied over the voyage being ten to eleven months." https://archive.org/details/sim_illustrated-london-news_1851... /mode/2up?q=%22London+to+Calcutta%22 ("Illustrated London News 1851-04-05: Vol 18 Iss 477"). As I understand it, clipper travel would have been fast and expensive.

> I expect the "law" is not as simple as "1 month travel time"

Aka the article is complete bullshit.

No, I didn't say that. It holds up for most of history, except for a fairly small window of ~50 years where communication was faster than travel (after that travel was fast enough that almost anywhere was less than 1 month away).

I agree. Imagine a future where we find a way to send messages at/near the speed of light intergalactically but can still only travel at some fraction of it.

We can already send messages at the speed of light. The problem is that's still way too slow for intergalactic communication (the nearest galaxy is 2.5 million light years away).

Let alone that the Portuguese were in Brazil, and the Spanish in the _Philippines_, for some 300 years

The Philippines is a great example of how to break this rule; it was almost more a colony of New Spain than of Spain.

Basically converting the empire into a franchise operation? Or maybe a pyramid scheme? To enable it to scale out beyond that range?

The VOC played a similar role in extending the Dutch empire’s reach.

The Philippines has never been easy to grasp though. Even now the government maintains poor control of many of their thousands of islands. Colonization efforts there can be profitable but are also weak. To the extent the Philippines has been colonized they must generally satisfy themselves to control of major ports and trade routes and naval bases.

Exactly. See my post elsewhere in this discussion where I give the transit times for goods from Madrid China via the Manila Galleons and the Mexican caravan routes back to Madrid.

There's so many exceptions. Does the article address any of these?

I didn't write the article so I don't care either way, but I think the British Empire was a thing totally on its own. Probably (probably, I'm not a historian) because its technology (both physical and organizational) was so much more superior to the lands they invaded that the normal "laws of empire physics" didn't apply.

In Australia (and NZ, and Canada, and the US, and probably in South Africa to a certain degree) their mode of operation seemed: reduce the locals to nothing (even worse than Spain), then build a fully Western-like society. Clean slate, mostly self-governed by white people who are not inclined to fight with Europe (with notable exceptions, obviously)

In India - although I don't doubt for a second they killed many many people - they seemed to operate more like the Golden Horde in Russia: as long as you pay the taxes (and occasionally provide more stuff when we run out), you can keep your culture and be governed by your local warlords, because it's just too tedious to kill all of you at once. The British did seem to have a bit more sway though, for example when they kicked off the partitioning, millions of people started moving. However, largely it seems like a brutal but mostly hands-off rule (based on mutual benefit with the local elite?)

What they did in Africa was something else, I've read books about insanely remote places like South Sudan or Zambia, and what were they doing there is hard for me to understand at all. But again, the gap in technology between the local people and them was so vast that they could do whatever they wanted without much coordination with the capital.

The Romans and other empires of the past were different because they didn't have such a huge technology gap. In case of Romans, you still fight it out with spears, swords and bare hands, and they tended to take over the lands completely, and impose their own gods, order and culture, which is much harder to do with a similar level of technology and does require coordination with the capital.

British Raj is a great argument for the article, started in 1858 and lasted less than a century, a blip in the historical context, as power projection was a recurring problem.

were they ruling it or plundering it for most of that time, and after they started ruling, how long did it last?

One could argue the British augmented that by creating better local institutions in the far away places.