This early 19^th century surveyor's cross arrived in the collection in December 2016. The instrument was made in the first half of the 19^th century by Pasquale Cittelli, an instrument maker from Milan, Italy (see below).

Basically this instrument is a round equerre that can rotate around its basis. The cylinder is made of a single piece and has eight visors at 45 degrees angles similar to the equerre. The cilinder is mounted on a divided base (see figure 3) and has a decimal vernier at the bottom dividing the degrees on the limb of the base into tenths (see figure 6), similar to a pantometer. A pantometer differs from this instrument as it consists of two half cylinders, both equipped with visors, stacked on top of each other of which the upper rotates in relation to the lower.

The main difference between Cittelli's instrument and the pantometer is that a pantometer allows to set or measure an angle between the visors of the two halves of the cylinder, while Cittelli's instrument can only measure the angles as a theodolite or cercle d'alignement.

The instrument seems to be signed "Cillelli" (see figure 5). The l in the first "ll", however, have a different loop at their bases than the second two, making it very plausible that either the first or the second should be "tt". As "Cilletti" is not a typical Italian name, "Cittelli" is more likely.¹

Pasquale Cittelli (29 October 1777 - 29 April 1838),⁷ also spelled as Citelli,² was an instrument maker from Milan, Italy.³ Three address are known:

• Corsia dei Servi 612 (see figure 3);
• next to the bridge near Porta Tosa (see figure 3, now piazza Cinque Giornate);
• Via S. Damiano 8.⁶

He was awarded in 1815 a silver medal for an instrument capable of measuring distances and heights, and for a large circular dividing engine under construction, for which upon completion he was awarded a gold medal the next year.³ From his workshop a plane table alidade resides in the Collection of Historical Scientific Instruments at Harvard University, the box of which contains a trade label of his firm (see figure 3).

In 1823 he published a 33 page work on a method for dividing plate vials used in astronomy and geodesy.⁴

Although Cittelli died in 1838, his business remained open until 1866. Given the relative modern look of some of his other instruments, it seems that instruments were still manufactured under his name until that year. What happened to his business after 1866 is unknown.

Clearly Cittelli was active in the fields of surveying and astronomy, and it is thus of no surprise to find this modified equerre with a divided limb by his hand.

Cittelli's major successes were from the mid 1810s. The instruments he made clearly were of much more complicated design than the one shown here. Still, the elaborate turned wooden container seems to indicate that this was not an ordinary off-the-shelf instrument, but that Cittelli was proud having created it. Most equerres and pantometers came in simple square boxes, just like the ones in my collection, that were easier to manufacture.

Although no evidence has yet surfaced, it could well be that this instrument was made by Cittelli in his early years and that it pre-dates the pantometer, which was invented in 1823.⁵ On the other hand Cittelli continued until 1866, so the instrument could be much later.⁶ Hopefully one day a dated catalogue will turn up, showing exactly this design, so this hypothesis can be confirmed or falsified.

The instrument was sold by an antiques dealer in Italy and survived the journey thanks to careful packaging. It came complete with its original turned wooden container, which seems to be made of oak. The threaded lid screws onto the container.

The limb on the base of the instrument is divided in hole degrees, all the way around. The vernier has 10 divisions (see figure 6), allowing to read the angles down to 0.1 degrees and even estimate to approximately 0.05 degrees.

The conical handle of the instrument has a steel screw with a brass knob (see figure 8) that allows the instrument to be firmly attached to a tripod, so that the base will not rotate during operation.

Not only the container is beautifully turned but so it the top of the instrument (see figure 7).