The Weight of Mystery

In the popular 1981 action film, Raiders of the Lost Ark, Indiana Jones battled Nazis seeking the lost Ark of the Covenant. As described in the Bible, the Ark was a gold-covered box of acacia wood with a lid of solid gold, built as a container for two stone tablets on which were written the Ten Commandments. It was carried ahead of the people during the days in the wilderness when the Hebrews were en-route from Egypt to Canaan. But when it wasn’t in-transit, it sat in the inner sanctum of the Tabernacle and, later, the Temple in Jerusalem.

A Seemingly Simple Question

The instructions for how the Ark was to be constructed are provided in Exodus 25:10-22. A few weeks ago I was reading a commentary on Exodus and, thinking about the slab of gold forming the lid and all the other gold used in its construction, I had a very simple question: How much would it have weighed? Could it have been easily carried by four men?

It seems like it should be easy to calculate an answer. We know the density of acacia wood (0.54 g/cm³) and gold (19.3 g/cm³). Exodus 25:10-22 provides dimensions for the Ark’s length (2.5 cubits), width and height (both 1.5 cubits). But how long is a cubit?

A cubit is the distance between elbow and fingertips and the definition varies in different cultures and time periods (anywhere from 17.5 to 20.8 inches). A commonly-cited value is 18 inches (45.7 cm).

My thinking is that the Hebrew artisans who built the Ark for Moses would have learned their craft in Egypt. We know the length of the ancient Egyptian cubit from measuring rods discovered in New Kingdom tombs that are roughly contemporary to the time the Exodus is supposed to have taken place. The Egyptian cubit is about 52.4 cm so I’ll use that as the base measurement. This gives me 131 cm (51.6”) for the length and 79 cm (31”) for the width and height.

I am now able to calculate the surface area but to calculate the volume I’ll need to know the thickness of the wooden walls and Exodus doesn’t provide that measurement. Neither does it tells us the thickness of the solid gold lid nor the dimensions of the cherubim atop the lid.

Scene from Raiders of the Lost Ark. You can actually purchase a kit (http://goldenarmor.com/arkhomepage/) that allows you to build a replica of the prop from the movie

Feast of the Assumptions

What have others come up with in estimating the missing dimensions? A simple Google search for “how heavy was the ark of the covenant” returned wildly varying answers.

WarrenMyers is one of the first results that pops up in Google, which is unfortunate because his assumptions are unsupported and his math is questionable. For example, he assumes the walls are 2” thick but calculates the wooden part of the Ark weighs only 25 lbs (based on Myers’ assumptions my math says the wood should weigh over 240 lbs). He estimates 104 lbs for the cherubim and guesses 1/32 inch (0.8 mm) for the thickness of the gold plating, eventually determining a total weight of 615 lbs.

Another of the top hits, JacquesGauvin uses some ridiculous assumptions. He assumes 3” thick walls, making the wood portion 413 lbs. His carrying poles are 6” diameter, more like fence posts. His cherubim are 1000 lbs. He guesses 0.125” (3.2 mm) for the thickness of the gold plating. His Ark finally weighs in at a whopping 4763 lbs. That’s more than twice the weight of all the gold Exodus 38:24 says was used in construction of the entire Tabernacle!

These two examples illustrate a couple of points: 1) unconstrained assumptions can vary wildly and 2) gold is the major determining factor in the weight. In Gauvin’s example, even if the weight of the acacia wood is reduced to almost nothing, you would still have an Ark weighing in excess of two tons due simply to the amount of gold used in his estimates.

Scientific Wild-Ass Guesses

A more thoughtful exercise is taken by ElihuSchatz. I found his Jewish Bible Quarterly article well after I had already started working through the issues on my own and was pleasantly surprised to see that Schatz had also identified gold as the key factor. Schatz’s Ark weighs in at 183 lbs mainly because his gold overlay is only 0.2 mm thick. But unlike the wild guesses of Myers and Gauvin, Schatz arrived at this thickness through deduction.

Exodus 38:24 tells us that 29 talents and 730 shekels of gold were used in the construction of the Tabernacle. This includes not only the Ark, but also an incense altar, table, lampstand, and the walls of the Tabernacle.A talent was 3000 shekels and archaeological evidence tells us a shekel weighed 11.3 g. In modern measures, 994 kg (2187 lbs) of gold were used for all the items in the Tabernacle.

Schatz writes (p. 116), “I calculated the total weight of the gold for all the vessels [in the tabernacle], and had to use a thickness for the gold overlay of 0.02 centimeters in order to approximate the value.” He cites the calculations made in his commentary (in Hebrew) on the book of Exodus, so I’m not able to see how he arrived at his conclusion but independently I had run some numbers on my own and arrived at the same figure. I originally was concerned that it might be too thin and would scrape off, but subsequent research told me that 0.02 cm (0.2 mm) is twice the thickness of the side of an aluminum can, so it seems that a gold overlay of that thickness would be durable.

I do have quibbles about some of Schatz’s other assumptions. For example, he estimates the walls of the Ark were 1.0 cm thick. This seems too flimsy and 2.0 cm would be more realistic. An article from the Metropolitan Museum of Art references (p. 130) an ancient Egyptian royal coffin from 2680 BCE “made of plywood, the six layers arranged with the grain running in alternate directions for strength and to prevent warping.” Each of the six layers was an eighth of an inch thick, giving a total thickness of ¾” (1.9 cm).

Also questionable is Schatz’s assertion that a 1-mm layer of gold for the cover “would have sufficient structural strength” (p. 117) to hold up his 25-kg (55 lb) cherubim. Gold has about the same elasticity of aluminum. A 1-mm piece of gold the size of a stick of chewing gum could be easily bent in your hands, so I have my doubts about its structural integrity. The inner coffin in King Tut’s tomb is made of solid gold with a thickness of 2.5-3.0 mm. My reasoning is that the ancient Egyptian goldsmiths knew what they were doing, so 3 mm seems a more realistic estimate for the thickness of the Ark’s cover.

On the bright side, I consider Schatz’s estimate of 25 kg for the two cherubim realistic. I base this on the fact that King Tut’s famous gold mask is 54 cm tall and 39 cm wide and weighs 10 kg. For comparison, the angels on the Raiders prop are 16.5” (42 cm) long and 8.75” (22 cm) tall. I think the cherubim may have been standing figures instead of crouching as in the angels from Raiders. The cherubim may also have been bigger than what the moviemakers had in mind. No one knows. But I think an estimate of 25 kg for the two cherubim puts us in the right neighborhood.

Multiple views of King Tut's gold death mask.

Putting it All Together

To arrive at an estimate for the weight of the Ark, I need to determine the weight of the acacia wood used to construct the chest, add the weight of the gold overlay, then the estimates for the solid-gold cover and cherubim. There’s also supposed to be a gold molding around the edges and rings to hold the carrying poles, but those comprise only a minor fraction of the total weight. Considering all the estimations and approximations, we can only hope to be in ballpark range for the total weight anyway.

The weight of the acacia wood using my preferred 2-cm thickness comes out to be 47 kg and the gold overlay of 0.2-mm thickness is 33 kg. The weight of the solid gold lid is 60 kg and the cherubim 25 kg. Almost half the weight is in the chest and the other half in its cover. The center of gravity would be around the point where the lid comes in contact with the chest.

The total weight using my estimations is 165 kg (362 lbs) and more than 70% of that weight (118 kg) comes from the gold. Four men could lift it but couldn’t be expected to carry it very far for very long.

Using a shorter cubit (such as the 18” cubit) dramatically reduces the estimate to 131 kg (289 lbs). Decreasing the thickness of the gold overlay to 0.1 mm further reduces the weight to 119 kg (261 lbs). Using 2.5 mm for the thickness of the cover marginally reduces the estimated weight to 111 kg (244 lbs).

As you can see, small changes in the variables can increase or decrease the estimated weight by 33% or more. You can come up with various reasons to tweak the numbers to get the weight of the Ark (and its contents) down to 180 lbs, and it might work if you only consider the Ark in isolation, but any of these tweaks will affect how much gold you end up using for all the Tabernacle items. Reducing the length of the cubit, for example, reduces the surface area of not only the Ark but all the other Tabernacle items and the amount of gold that would be needed to cover them.

Now that I have an idea how much the Ark could have weighed, in my next article I will discuss some observations I drew from this analysis and examine the question as to whether the Ark ever existed at all.

Echoes of Egypt

In the last few articles, I’ve reviewed the archaeological evidence that the Israelites emerged from the existing Canaanite population. There was no military conquest in which migrating Israelites displaced an indigenous Canaanite people as recounted in the biblical book of Joshua. The only thing that seems to set “Israelites” apart from “Canaanites” is their distinctive style of house and a lack of pig bones in their garbage dumps.

Examining the source traditions that make up the Bible, the Elohist (E) and Priestly (P) traditions insist that the divine name of Yahweh was revealed in Egypt. While the deity may have been known under the Canaanite name of El in the past, his real name is Yahweh. The worship of Yahweh as the chief deity is another distinctive belief of the Israelites.

Is there any evidence that a small group of people may have migrated from Egypt to Canaan, bringing with them some of their religious traditions, including a belief in a god named Yahweh?

Egyptian Names

The exodus and wilderness narratives mention several individuals with names that seem to be Egyptian in origin: Hur, Phinehas, Merari, Mushi, and of course Moses.

As odd as it may seem, one of the most frequently-mentioned names in the OT is not Hebrew in origin. The name Moses derives from the Egyptian mose, “is born.” We see it frequently in the names of the Egyptian pharaohs like Thutmose (“Thoth is born”) and Ramesses (“Ra is born”). In the case of Moses, the name of the Egyptian deity was lost.

Hur was the companion and assistant of Moses and Aaron. His name derives from the Egyptian god, Horus. Phinehas was the grandson of Aaron. His name derives from the Egyptian words meaning “the southerner.” Merari was the third son of Levi and Mushi was his son. The name Merari derives from the Egyptian words meaning “to love.” Mushi has the same derivation as Moses.

To be clear, Egyptian names alone mean nothing. Someone composing the stories centuries later could have made up Egyptian names to provide verisimilitude to the story. But when it comes to Moses, it does not seem as though the tradition realized his name was Egyptian in origin.

In the story of Moses being rescued from a basket (Ex2:3b-10), the Pharoah’s daughter called him Moses (Hebrew mosheh) “because I drew (Hebrew, mashah) him from the water.” She’s making a pun on the name as though it were of Hebrew origin, not a shortened form of an Egyptian name. It’s as though she is saying, “I’ll name him ‘Drew’ because I drew him from the water,” not realizing that “Drew” is a shortened form of the name “Andrew”.

The evidence suggests the name of Moses was handed down in the tradition but not its Egyptian origin. Those who later wrote it down came up with a Hebrew derivation for the name. This militates against the idea that Egyptian names were created to provide local color to the story.

Pharaoh’s daughter finding baby Moses by Konstantin Flavitsky (1830–1866) 

Egyptian Artifacts

Seven chapters in Exodus (25-31) provide the blueprint for the Tabernacle and its furnishings and six chapters (35-40) describe how those instructions were followed in its construction. As the Bible relates it, the Tabernacle was the center of Israelite religion in the pre-monarchial days just as the Temple was central to worship in the days of Solomon and beyond.

As befitting a people on the move, the Tabernacle was essentially a fancy tent with the Ark of the Covenant in its inner sanctum. As Moses and his people left one campsite, they would disassemble the Tabernacle and carry its furnishings (the Ark, lampstand, altar, etc.) to the next campsite where they would then reassemble it until it was time to move again. Once the Israelites reached Canaan, the Tabernacle was eventually established at Shiloh until David had the Ark moved to Jerusalem.

Just as the Exodus is questioned as historical fact, biblical scholars and archaeologists have doubted if such a Tabernacle ever existed. Some think it was the Priestly author’s idea for a scale model of the Jerusalem Temple adapted for desert wanderings. Others have found parallels in tent shrines built by neighboring people.

Perhaps the best comparison for the Tabernacle as described in Exodus may be the battle tent of the Pharaoh Ramesses. Both feature the main tent situated inside a courtyard. The battle tent is divided between a larger reception area and the inner sanctum where the Pharaoh resides. This matches the Tabernacle with its larger Holy area and the inner Holy of Holies where the Ark of the Covenant, the footstool of YHWH resides. The 2:1 proportions between the inner and outer sanctums are roughly the same in both.

The Ark, too, has an Egyptian parallel in the sacred bark, a ritual object resembling a boat, usually carried on poles by priests in procession. Its main purpose was to transport gods and mummies.

A Tribe Called Levi

Looking back on the evidence so far, a pattern begins to emerge. References to Egypt as the location where God revealed his name as YHWH only come from the E and P sources, both of them of Levite origin. Of the individuals mentioned with Egyptian names, the Bible tells us most belonged to the tribe of Levi. The Tabernacle and Ark are strongly tied to cultic practices which could only be undertaken by members of the tribe of Levi.

Could it be that a small group who escaped from Egypt became known as the tribe of Levi?

References to the Levites in the Bible are not consistent and somewhat confusing, but two points stand out: the Levites were not given a territory of their own in Canaan and were the only tribe allowed to serve as priests. These are not unrelated.

Outside the urban economy of the Canaanite city-states, there was little opportunity for artisans, craftsmen, and so on. Most of the residents of the Canaanite hill country needed land to grow food for subsistence. If an incoming group from Egypt arrived after territory had already been doled out to various clans and tribes, they would have found themselves landless and in need of a way to make a living. Serving as priests of the central sanctuary of Shiloh and at local shrines throughout the countryside would have sufficed.

These Egyptian refugees would accommodate their religious beliefs and practices to those of the indigenous Canaanite population. The god Yahweh that they had worshipped in Egypt (and perhaps earlier if they were originally from Midian) would be recast as another name for the Canaanite god El who the locals already worshipped. As the official teachers of religion, the Levites could instruct the Israelites in the Egyptian practice of circumcision, the kind treatment of slaves, and tales of the plagues.

Because they were resident aliens, perhaps it is not surprising that the Levite sources in the Bible commands 52 times that resident aliens are not to be mistreated “because we were once aliens in Egypt.”